I do almost all of my own work on vehicles now. Just wanted to say that this video is the one that really started it all. Before this video, all I was doing was oil and brakes. I used this video to fix my first alternator problem. I bought a new alternator (like a typical swapper!) but because of this video, that part sits on my shelf brand new to this day. Because the troubleshooting (and specifically the drop tests) helped to definitively locate the source of the problem, which was a loose and dirty alternator hinge bolt on my 2004 subaru outback. Before then, I didn't even own a multimeter, and I literally had to walk step-by-step through this video. The tests help literally isolate the problem down to just a few inches of possible culprits. It totally changed my thinking, and ignited my interest in learning more. I have since done the water pump timing belt on a 2003 v6 Accord, axle ujoints, hubs, rebuilt drive shafts, installed lift kits, and helped a lot of people not get screwed by shops. I plan on making this the year that really increase my electrical diagnostics skills. I have a 96 Cherokee XJ that I love, so it will be enjoyable, but probably also necessary to know. Taking an old Jeep to a shop every time you have an electrical problem is a good way to go broke, and not have your vehicle for weeks at a time.
Im about to join you,I too like and enjoy this video and am hopeful to get to the bottom of my issue by using this video. 2003 Mitsubishi Eclipse GTS V6 5-Speed At first the Alternator would work sometimes now it completely died,Im not sure but I suspect the previous owners wiring charade was the original cause.Theres an amplifier hooked up that constantly drains even with the ignition off.I have a son on the way,and I have to get this fixed asap before Every dollar gets spent on the baby lol. Im going to just replace the alternator and hope for the best,But will be testing the new system using this video to hopefully pinpoint any problems I might have.
Yup..amazing, right...do all my brakes now (Honda Pilot...saved me what ? $2-300, labor ?) ...and did This Check...Feels good, right..ERIC Saves Us Bucks...and Empowers DIYers !...Kudos, Eric the CarGuy !..THANKS !
I was happy to hear someone stress how important it is to check connections before replacing a part. I did it after watching your video and wala, it saved me from buying an alternator. Great video Thank 👍🏼👍🏼
As an Industrial electrician, I learn something new almost every day. Your videos on car troubleshooting are great. Keep up the good work. A video on how to replace the battery cable to the alternator on a 1998 Audi A4 would be sweet.
Thank you for this! I took me all of ten minutes to diagnose and fix my no start/weak start condition. All it took was multimeter and a few minutes to patiently probe everything I needed to look at. Saved a ton of money. Started at the battery like you said, checked for proper voltage off and with the car running and a load put on the system., then removed the terminals,.cleaned up the wires, terminals, and posts, reconnected everything nice and securely, fired it up and without hesitation, she came to life purring like a kitten. Went through the rest of your steps, then last, went to the alternator, serpentine belt etc. and tested them for proper tension, readings, and operation. They also passed with flying colors. Took her out for a test drove close to home several times after the fact..all is back to normal. Amazing how a little corrosion on the battery terminals could wreak such havoc on a system, so I also checked all of the wiring for good connections etc.. A nice wire brush and even some contact cleaner got everything looking spic and span. Now to solve my door ajar light issue lol! please help. I tried lubricating the door latches but I'm still getting the door ajar light,.had to remove my dome light bulb. It was killing my battery. Doors are closed but the light would stay on.
Thank You. Perfect. I like the no nonsense presentation too. No hand waving, no attempt to make buddies, no guitar overlay, no trying to show off or act cute.
this is 9 years but the youtube search brought me to one of the best car mechanic on yt. even these days there is nobody who can lay it out better than this guy ..
I keep coming back to you Eric......As a mechanic I have varied responsibilities with a multitude of equipment. I need to stay on top of things and you are one of two persons who I watch regularly. Dan Sullivan being the other makes it possible to stay informed. Thank you
Great video, Dealer said over $500 for alternator part only, Advance Auto re-manufactured one was $130 w/ core. So far the new alternator is fixing the problem.
Thanks , I was showing bad alternator, I got new one put it on. Same thing. Watched your video I found a ground issue. Quick fix now it's working great.
great video !!!! i am a tech for over 25 yrs.,but still like to watch back to the basics videos just to keep kinda brushed up !!!! however, as far as the computer controlled voltage regulator, i've only really seen dodge to be the worst !!!! and of course most customers don't believe you and go some where else !!! after that ,....who knows what happened !!! thanks for your videos !!!!
I am so happy I've found this channel. I love doing work on my own car and have been increasing my collection of mechanics tools. I recently just changed the valve cover gasket on my car which on a normal car wouldn't be that difficult but my car is a VW Scirocco 2.0 tsi and it doesn't even have a gasket. It uses anaerobic sealant. To get the valve cover off, the vacuum pump, hpfp, pcv and upper timing cover needed to come off. I'm watching every video you have made Eric and I hope you keep making them because there is nothing better than being able to fix your own car. Thank you so much for the time and effort you out into making these videos. Take care and stay dirty.
dude, i appreciate all your videos. you start with the basics, discuss theory of operation, cover variations and then work your way through a logical flow chart all the way to the end and then beat on things to not over look and then conclusion
Scotty you are main reason why I stop taking my car's to mechanics.Stuff that I thought was hard to fix you made it look easy.Just watching your videos did the trick. Thanks for all the videos.
Great video, Excellent troubleshooting flow chart. Thanks for the tip of checking differential voltage on positve/negative sides. as for oddsn'ends comment below: The author doesn't mention disconnecting your battery while running because this method if frowned upon with newer vehicles. That test can actually blow components. The battery acts as a filter cap and when your alternator spikes to 18v even for a nanosecond, you can potentialy destroy electronics because they operate at 12v with a small tolerance. You could get away 13, maybe even 14.5. It is dependant on the circuit and is risky even though it may seem to work. On older vehicles like mid 90's and below no problem. The test methods provided in this video may take an extra minute using a multimeter but it enables acurate diagnostics and less work. You don't need a socket to pull a terminal. That saves time. Thanks EricTheCarGuy!
Great video, Eric - always start with the simple reasons: corrosion on battery terminals, loose connections, loose belt. There it was - loose belt. $7 later alternator properly recharging battery.
man the connection issue is no joke! just went through two days of hell and may have killed another battery before i found a loose ground wire on the alternator. tightened all my connections last night. car started right up this morning. THANK YOU
Thanks for posting this video Eric! You've inspired me to learn about the Multimeter I've had for 10 years but haven't taken the time to educate myself about it, and how to diagnose my 2004 Santa Fe alternator/battery problem. Keep doing what you're doing ;)
Eric, y're my hero, had some problems with charging, removed the alternator, tested it inside - outside, shit could not find the problem, finally I decided to search your channel, and there it was, the mass cable between the engine block and the body was corroded, I had a voltage drop of 1,6 V with almost everything on and the engine running idle, it went to the roof when I turned up the rpm. Thanks man, you saved me a lot of money again.
One more test to do is to measure the AC voltage across the battery terminals while the car is running. It should be zero, but if it is higher it means a diode is no good and needs to be replaced. Great Video!
I haven't fixed the gauge yet, but I think that is the issue on an older truck that I have. Saved me about 40 dollars in parts and the grief of replacing those parts. Thanks Eric.
Your videos are always a great help. Thanks for dedicating so much time to make these. I run a lot of electronics in my vehicle and my Honda only maintains the battery voltage it doesn't really charge it. I also need a HO alternator and was curious if a self exciting one that constantly ran at 14.8v would damage anything?
I recently started doing as much work as possible on my own cars. Recently the battery light came on in one of our vehicles, I found this video, and solved the problem in just a few minutes. I was ready to go get a new alternator. After walking through all of the steps, I discovered that the belt just needed to be tightened.
Thanks!!! Your videos are consistently the best car videos I've seen around. Good solid advice and how-to's, with specific information such as what's shown in this video. I learn something everytime I watch one of these, and my wheels are still rollin'. Thanks a ton!!!
Big Help, Eric !..Did all these test for a low, weak crank this morning. 2 year old Interstate pricey battery. Charged the battery. Got all the right readings as per your instructions (even not above 60 degrees ambient). So...Hahahaha...Why the weak crank this morning. Car had been sitting for only 3 days. 28 degree nites. Hmmmm
This video just saved me from buying a new alternator. Turns out one of the wires had broken inside the socket so it wasn't that obvious at first glance. Thanks man!
Eric. I have great respect for your diagnostic events. Working on a 2006 E250 Econoline 4.6L Van. The alternator gets very warm even with the engine not running. Engine cranks, won't fire. No spark, no Schrader valve found to check fuel pressure. Tried quick start but nothing of course. Replaced Alternator (tested and found faulty) after it fried the battery and lights came on very bright in cabin. Truck finally died and was towed here. Rebuilt alternator is also very warm without engine ever running. New Computer NA. Thoughts?
My sons Exterra had a battery light on, with the car started was only getting 12.4 volts felt the terminals was very hot ! Turns out he just replaced the battery but had a loose connection! after cleaning and tightening it was charging at 14.3 v Thank you So much Eric I always tend to watch your Video's, Good content with out allot of fluff!
Great Video very informative. The only thing I saw for a recommendation is when Checking for voltage drop. You should set the meter to 2V not 20v, though in this case it would still pass. The meter should give you one one more digit of resolution in the 2V range.
Well Eric you saved the day. I had coolant issues with my 2001 Honda Civic. besides the cooling fan the thermostat was not working right.The thermostat was new. After watching your video on thermostats I found it was with that little value on the bottom. After the thermostat was put in THE RIGHT WAY all air was able to be removed.This isn't about alternators but thanks so much. By the way I have a 1956 firetruck that is positive ground. I had some charging problems. You videos have helped me out. Thanks.
please note also, and yeas ago, we chased this problem for a few days. another thing to be aware of, is when you turn your key to the run position, the batter light should light up. if the battery light is burned out, it will not trigger the Alternator (Voltage Regulator) to begin charging. In the case f the vehicle we were chasing the problem on, My Boss, was "exciting" the Alternator At the field tab on the Alternator, And the car would begin to charge just fine till the car was shut off. Shut the car, start it again, Not Charging! Excite the Field, System charging until Car was shut off. WTH? This was in the days before internet, So I went home and did a bunch f reading (from real books.....LOL). It never really said "Hey, if the battery light is burned out, the car won't charge" I had to "read between the lines" Went in next day, replaced Alternator/Battery light in the dash, Car started, and began to charge.
I would never take my car to a mechanic unless it's something I really couldn't do like transmission band adjustments or getting an alignment done. It just feels wrong to have someone else touch my car with out me being part of it
George Clooney lol . I have only just found your channel, I have to thank you for taking the time to do so , I've just watched your battery drain video and im having the same problems with my KTM. I've found out I have a 5.5amp drain and pulled the fuse out of the solinoid and it goes to 0.00 so now at least I have some awnsers. Man I love you.! I fear my alternator has also gone .so here I am .
Thanks so much, I had a flat battery this morning, changed it but was still worried about the alternator, but thanks to your video I've just tested it and found it to be absolutely fine! :)
Thanks for the excellent video Eric. It was very helpful. Mine turned out to be the fuseable link near the pos battery connection. It was fried. Am assuming that one of it's functions was to provide exciter voltage to the alternator. Also great to find out that the ecm could be controlling the alternator and that it can be bypassed in a pinch.
Hey Eric, first of all have to say mad respect brother. I've done many things and taught myself over the years and you have helped me a lot! Idk if you have ever worked on a Mazda tribute 3.0 or ford escape alternator. But I'm facing that soon and its no joke. Now before I do that ridiculous job I want to make sure it's not the ecu like u said. How can I test that? If I jump the car it shuts right off immediately. It is getting fuel bc it started. Battery is dead but I'll charge that up and test the alternator. But how do I check computer?
This truly is a great video. Nice refresher course for me, since I do do my own work, but not regularly, so I forget a few things, this video helped me refresh my knowledge. Thank you very much.
Eric, I would recommend starting the video with a highly detailed and thoroughly explained drawing that communicates what we're going to be doing in the video before we actually do it. Because of multiple shots and camera-off and camera-on, it's easy to get lost while viewing and not receive what you intended to give. I've watched this multiple times and am still confused. Thank you.
Thanks for videos. They have helped me when working on son's 98 4runner. I had an issue that seemed intermittent but was certain it was an alternator problem. Issue happened a couple of times again after checking all connections. First time testing alternator all tests passed. Performed again a few days later with diff test set and found diode test was failing. So, I got a rebuilt alternator from X part store. While testing in evening with lights on (eight miles after installing the alternator), radio and lights blinked. It blew the low beams. I installed the old alternator in parking lot so that I could get it home. I didnt want to take a chance on blowing high beams while trying to get home on new alternator. Took the new alternator to X where they tested new alternator - tested fine. It did not blow any fuses so I determined that it was not a high current issue but high voltage issue. X gave me another alternator and have had no problems. I still think it was a regulator issue with the 1st rebuilt alternator. Thoughts on supporting my theory. X would not replace my bulbs because of their alternator tests. Not happy because these bulbs are $25 for each. Thanks SteveBurke
Best video I have seen on this topic. My 2004 Expedition "Check Charging System" randomly beeps, when it rains. Then went crazy beeping for 4 hours on my last trip in the rain. So we had to turn the radio up to full, for our sanity. The next day no rain, no beeping. New battery, alternator tested fine. I suspect a wiring harness?
For diesel owners: If after starting the voltage is near or below battery voltage, the glow plugs may still be on. Glow plugs draw a lot of power and in some systems may be still be on for a minute or two after the engine is started. Either wait until the glow plugs shut off or disconnect the glow plug relay prior to starting.
It's not done the same as the negative. The positive side is tested between the positive battery terminal and the post on the back of the alternator, the one that was a wire bolted to it.
Manufactures do not make adequate ground for alternators. That is the problem. If they did, they would last longer and have more stable voltage. Bolting a alt to engine is NOT enough ground. Grounding alt body to chassis is better but still not enough. The only way to properly ground a alt to work optimally is to take apart alt and modify casing so that you can secure a 4gauge wire to the B- (negative side) of the rectifier bridge directly to the battery ground post. Do this and no more voltage/amp drops (assuming everything else is good).
Hey Eric great video. Maybe i missed it but I only seen you do a resistance test on the the neg side but not on the pos side . You did mention where to test on the pos side do you use the same limits/scale on the pos side .1 to .2 volts resistance?
working on cars.. voltage drop testing do you have a digital voltmeter..set it to 20 volts DC. engine off.. headlights on for one minute. then turned off.. check battery voltage.. 12.65 is a fully charged battery. 12.45 is a 3/4 charged battery. 12.25 is a 1/2 charged battery. if you have less than 12.5 volts have your battery charged and load tested.. once you verify that the battery is close to a full charge after you have removed the surface charge with the headlights on trick... get the engine started... turn the headlights back on.. Negative battery post to the positive battery post.. 14.1 to 14.8 volts is expected.. Negative battery post to the engine block. 0.04 volts DC MAX.. Negative battery post to the body of the car.. 0.02 volts DC MAX. Engine block to the Body.. 0.02 volts DC. if you get more than the 0.04 or 0.02 volts on tests 2, 3 or 4.. you have a bad ground connection.. you can and should also.. after running the voltage drop test above.. test from the battery post to the alternator output terminal.. because of the amount of output.. i normally expect this to be up around 0.07 volts..
If u do have a bad ground connection how do u fix it? I have a honda civic 2015 and I just replaced the alternator and the battery and the cars battery connection light came up
You did a good job stressing the need to check connections. I'll take it a step further and say that when I have electrical issues I start by disconnecting the battery cables and cleaning the posts and terminals. Especially those side post batteries. They can hide corrosion at their connections. And unfortunately a voltage drop test won't show bad battery connections. Cheers.
never do the alternator test by removing negative cable on newer cars!!! or u will fuck something up. That shit worked fine with older cars but not today!
You neglected to mention a "slack" tensioner on the serpentine belt (if your car has one). These sometimes fail to maintain proper tension on the belt when the engine is operating. A "slick" belt can also allow inadequate friction between the belt and alternator pulley especially if the "back side" rather than the grooved side of the belt of the belt spins the alternator pulley. Wear causes the belt to become slick as if it were greased and can cause slippage. Check to see if some wires may have been chewed by a rodent or squirrel. Those animals are capable of chewing copper wires completely through. It happened on my Ford F350 Diesel when Mama squirrel built a nest under the hood and mothered 4 little babies in warm weather. I removed the nest and found that she had chewed an electrical wire completely in half when she built the nest. The engine would not even crank until I put the wire back together. Then it worked fine. The baby squirrels apparently have grown into adults and occupy trees around the house. No more trouble from them though. .
I've been a long time subscriber and I'm glad I decided to check your video before buying a new alternator! Saved me some money and time, only needed to clean the contacts!
I'm going over videos today of you and Scotty as I figure out what's wrong with my 2000 Corolla. Alternator checks out for a load test, but the battery doesn't, and it's less than 2 years old. There's a lot of rust under the car, so I'm going to check my wiring connections and my grounds. Thanks for everything.
Super great info much appreciated. I changed my terminals hoping it was it as the old ones were old N a tad corroded. The weather has been really cold after it started with a jump I failed to start for a few days so it was drained.
I went through all these tests because I couldn't find a parasitic draw. The truck sitting still and off was drawing about .84 amps with the key off. I pulled all the fuses one at a time, and didn't see an amp drop on any of them. When I checked from the battery to the alt casing, I got the .84 amps again. After checking and cleaning all my connections, I still have the .84 amp draw condition. But the alternator passed all the tests. Does this point to a bad diode within the alternator? The only other part I haven't checked is what appears to be a fuseable link in line from the alt running back to the dist. area. The truck runs and seems to charge the battery fine, but when it sits for more than a day, the battery is dead. Would this be caused by a bad diode? OR, should I go the extra mile and check my connections at the starter as well?
Interesting that in no comments asking for add'l info does Eric ever reply here... (Maybe on his web site) so all you'll get is other opinions from other people who also don't know how to fix similar problems... GRRRR...
Dude You are for certain THE MAN.. only wish You were My Mechanic.. Sooo hard as a Woman to trust any Car Mechanic.. years of bad experiences ruining my Cars..We Learn alot from Your Videos. You're a good Auto Instructor.
IF you START the video at 10:45 and end at 10:54 it appears as if the draw goes to .02 then .03 and you said that for this test it only registered .01. My question is not as a criticism but is it okay if instead it reading .01 it does read .03 would that be a unfavorable outcome? Perhaps you didn't notice the reading or it is not relevant? I'm just curious. Seems to contradict what you stated before.
.01 - .03 is completely different from what he meant which is .1 and above which means there's too much resistance on a wire... It can be a corroded or rusty ground/connection on battery or a slit on a wire/broken insulation causing not all the power to get to its destination like say battery ground terminal to the ground on the chassis/engine block
Keep up the good work eric.One plint i should make that during alternator diagnosis qnd part of due diligence would be to set your meter to a/c volts and connect it to the neg and pos terminal of batt to see if any a/c voltage is present there. That would indicate one or more bad diods leaking unrectified voltage.This usually results in low alternator output numbers during a high load test and can also manifest in battery going dead when vehicles sits over night.
+Mike Harris I was wondering why we weren't discussing AC ripple also but that usually impacts stereos and ground loops rather than poor charging situations in my experience. AC ripple shows up really well on a scope also. I think anything up to about .5V is pretty normal on some older vehicles...
Samniss Arandeen if I am suspecting the alternator belt tension, (odd squeek at low RPM range and intermittent rough idle) could hooking up a 2nd battery (as if I were going to jump it, even though the car starts and runs), diagnose an alternator issue? If I connect a 2nd battery, it could smooth out the voltages, and if my idle issue goes away, then I know its power related?
Samniss Arandeen if I am suspecting the alternator belt tension, (odd squeek at low RPM range and intermittent rough idle) could hooking up a 2nd battery (as if I were going to jump it, even though the car starts and runs), diagnose an alternator issue? If I connect a 2nd battery, it could smooth out the voltages, and if my idle issue goes away, then I know its power related?
+Samniss Arandeen you wouldn't believe how many people falsely believe that by tightening their alternator belt, they'll fix an alternator problem...all they usually do is overtighten the belt, and burn out the alternator bearings..so yeah, 99.9999% of the time it is not belt tension...
This was a great video. I was going to replace my alternator, but now learning that you want to be .5 above the battery condition has me thinking twice. I have done a peristaltic test, I do have an isolator in my truck, same batteries, Interstate, same age. Took the truck to Good year, they ran the test, everything came up clean, but still battery dies after 3/4 days.
Man I remember when I first saw eric the car guy and he only had like 40000 subscribers now he has half a million good job eric I knew you would blow up one day
Older volvo bosch alternators are notorious for won out brushes. And they're cheap & easy to replace. Full fielding is a very handy test! And ground straps can get corroded on all cars. A continuity check from alt case to batt neg terminal takes a few seconds, and finds problems fast. Then polarizing old generators... Just googe it. lol. great vid!
I had a Nissan Pathfinder that when running, would actually blow out the headlight and the heater motor sounded like a roots supercharger! This vehicle had a separate wire from the alternator to the battery post where the plastic connector corroded and failed so the majority of the charging was going right back into the car's electrical system and not the battery. The dealer wanted to change the entire engine bay wiring loom to which I told them to pound sand. A local car electric shop changed out the connector for $20. I also had a 1991 Camaro that wouldn't hold a charge so checked the usual suspects like you mentioned but couldn't find an obvious fault. This car didn't have a wire from the alternator to the battery but the positive battery cable had a mid point junction for the charging and accessories so in the end, had to change out the factory battery cable which was not cheap.
That's what mine is doing. I've blown thru 2 brand new batteries and 2 regulators, in the same day! I have a 1990 Ford van. With a 5.8 liter engine. Someone told me today that I should sell it for parts. So frustrating.
The first suspect is always the Battery, many auto parts stores now do load test on batterys for free to see if your battery is holding a charge. If the battery is ok, then proceed. Get a Volt meter that has aligator clips, disconnect the positive cable from the battery, leaving the negative cable connected to the battery. Hook the Positive or red cable lead from your Volt meter to the positive terminal on the battery and hook the Negative or Black cable lead from your Volt meter to the positive cable, makeing sure that the positive cable ends do not touch ground. With the ignition off, the Volt meter should be reading 0 volts, but if something is shorted or staying on, you will get a 12 Volt reading. Assumeing that you have a voltage reading, its now time to proceed to the next step. Completely disconnect the wires from the Alternator, keeping the wires from touching ground, and see IF the Voltage reading drops to zero, if it does, your Alternator has a shorted diode, the alternator will need to be replaced (common problem on S10 models) If the volt meter however remains unchanged, reconnect the wires to the alternator. The next step have someone watch your volt meter as you beguin to pull the fuses from the fuse box, if the volt meter drops to zero after pulling a fuse, it will give you an idea of what circuit is shorted, their by drawing electricity, while the ignition is off. Get a Chiltons Manual on your make and model, and look at the wiring schematics for that particular circuit.. Is this true? I Put a new Alt. on the trucj and still showed a 11.8v drain?
Nice video, a good linkable follow up would be a "mythbusters" of how NOT to diagnose an alternator, like "start car then disconnect positive terminal and see if car dies". etc.
+Snap-off - Go to Harbor Freight and get a *PLUG IN Battery/Alternator Tester* for $6.99 and NEVER have to worry about it again! YES... You will know ALL THAT 24/7 or when your Battery is not charging or Alternator is dead, etc... !!!
Thanks for the reply. I have a multi-meter and a college degree in electronics engineering, so I'm good on alternator testing, but I'll still check them out because little electronic devices like that fascinate me and are why I got into electronics engineering in the first place!
My car won't start at all. The last time I got it started I noticed that the alternator wire was smoking. I believe this is the reason that my battery died. What can I do about this and could you give me a reason as to why this might be happening?
Thank you Eric,you made it more understandable for me to wrap my head around my problem with my 1984 toyota camper that's on the 3rd alternator voltage problem/parking lights/volt light on !
I have to say what a Great video walking thru voltage drops and how to go threw a proper charging system and how to rule out other areas. I have a 2007 Dodge Ram 2500 5.7 L Hemi I have replaced the ECM Module and Starter a year ago. My Mechanic had my truck for a week he does a great job but I work for myself and dont alway have the money. I am having the same issue i had a year ago, I was coming home from a job and notice the battery discharging negatively and it got worse as the day went my alternator had a bearing hum replaced it and still having issues ALternator was not the issue but the bearing was showing wear. I know alot about motors and engines but I dont know everything Im a utility engineer and Im knowledgeable. This Video Made my battery and ECm and charging system easy to understand . Thank you for the Education......
Great video. It refreshes the small things a person may not think of. I hate those new smart charge systems where the charging is controlled by the ecu
acoow When doing the test on the positive side you touch the pos lead of DMM to pos on alt and neg lead to pos on battery, this will not hurt anything. in a nice DMM if something goes wrong theres a circuit breaker inside of DMM that will break before damage to car occurs. Im a certified diesel tech.
BassheadGTP Is this with the car running also? Can it be done with the car engine off, or even with the alternator disconnected? I mean, testing between the battery's positive terminal and the alternator's connector. I ask because it's impossible to get at the alternator's connector when it's mounted.
Once again another outstanding video. I will do some more troubleshooting on the Honda (battery and door light stays on until I rev up the engine to 2000-2500 rpm).
Your video covers everything. Great! I like do work in my 2004 Sierra SLE ext. cab 5.3L V8. I just got a new battery and now in the cold morning when starting the truck a warning sign comes up, "Battery not charging" and voltage drops to 9V this lasts for 20min till engine warms up, then voltage goes up to 14V. Is that a sign a have a bad alternator? Thanks!
EricTheCarGuy you should do a separate video sometime checking A/C voltage coming from either the battery or alternator (or excessive ripple) that can be caused by a bad stater or diode in the alternator, or a bad battery.
![Megan Thee Stallion - Roc Steady (feat. Flo Milli) [Official Video]](http://i.ytimg.com/vi/HozPPyqW0dY/mqdefault.jpg)
I do almost all of my own work on vehicles now. Just wanted to say that this video is the one that really started it all. Before this video, all I was doing was oil and brakes. I used this video to fix my first alternator problem. I bought a new alternator (like a typical swapper!) but because of this video, that part sits on my shelf brand new to this day. Because the troubleshooting (and specifically the drop tests) helped to definitively locate the source of the problem, which was a loose and dirty alternator hinge bolt on my 2004 subaru outback. Before then, I didn't even own a multimeter, and I literally had to walk step-by-step through this video. The tests help literally isolate the problem down to just a few inches of possible culprits. It totally changed my thinking, and ignited my interest in learning more. I have since done the water pump timing belt on a 2003 v6 Accord, axle ujoints, hubs, rebuilt drive shafts, installed lift kits, and helped a lot of people not get screwed by shops. I plan on making this the year that really increase my electrical diagnostics skills. I have a 96 Cherokee XJ that I love, so it will be enjoyable, but probably also necessary to know. Taking an old Jeep to a shop every time you have an electrical problem is a good way to go broke, and not have your vehicle for weeks at a time.
Im about to join you,I too like and enjoy this video and am hopeful to get to the bottom of my issue by using this video.
2003 Mitsubishi Eclipse GTS V6 5-Speed
At first the Alternator would work sometimes now it completely died,Im not sure but I suspect the previous owners wiring charade was the original cause.Theres an amplifier hooked up that constantly drains even with the ignition off.I have a son on the way,and I have to get this fixed asap before Every dollar gets spent on the baby lol.
Im going to just replace the alternator and hope for the best,But will be testing the new system using this video to hopefully pinpoint any problems I might have.
Yup..amazing, right...do all my brakes now (Honda Pilot...saved me what ? $2-300, labor ?) ...and did This Check...Feels good, right..ERIC Saves Us Bucks...and Empowers DIYers !...Kudos, Eric the CarGuy !..THANKS !
Jordan Moore
Good job
Close
I was happy to hear someone stress how important it is to check connections before replacing a part.
I did it after watching your video and wala, it saved me from buying an alternator.
Great video
Thank 👍🏼👍🏼
As an Industrial electrician, I learn something new almost every day. Your videos on car troubleshooting are great. Keep up the good work. A video on how to replace the battery cable to the alternator on a 1998 Audi A4 would be sweet.
l
Thank you for this! I took me all of ten minutes to diagnose and fix my no start/weak start condition. All it took was multimeter and a few minutes to patiently probe everything I needed to look at. Saved a ton of money. Started at the battery like you said, checked for proper voltage off and with the car running and a load put on the system., then removed the terminals,.cleaned up the wires, terminals, and posts, reconnected everything nice and securely, fired it up and without hesitation, she came to life purring like a kitten. Went through the rest of your steps, then last, went to the alternator, serpentine belt etc. and tested them for proper tension, readings, and operation. They also passed with flying colors. Took her out for a test drove close to home several times after the fact..all is back to normal. Amazing how a little corrosion on the battery terminals could wreak such havoc on a system, so I also checked all of the wiring for good connections etc.. A nice wire brush and even some contact cleaner got everything looking spic and span. Now to solve my door ajar light issue lol! please help. I tried lubricating the door latches but I'm still getting the door ajar light,.had to remove my dome light bulb. It was killing my battery. Doors are closed but the light would stay on.
Could be a broken door sensor wire in the harness to the door.
Thank You. Perfect. I like the no nonsense presentation too. No hand waving, no attempt to make buddies, no guitar overlay, no trying to show off or act cute.
this is 9 years but the youtube search brought me to one of the best car mechanic on yt. even these days there is nobody who can lay it out better than this guy ..
I keep coming back to you Eric......As a mechanic I have varied responsibilities with a multitude of equipment. I need to stay on top of things and you are one of two persons who I watch regularly. Dan Sullivan being the other makes it possible to stay informed. Thank you
Great video, Dealer said over $500 for alternator part only, Advance Auto re-manufactured one was $130 w/ core. So far the new
alternator is fixing the problem.
Thanks , I was showing bad alternator, I got new one put it on. Same thing. Watched your video I found a ground issue. Quick fix now it's working great.
I think Eric is my new favorite person on the internet. He's damn good at what he does and puts out really helpful videos.
great video !!!! i am a tech for over 25 yrs.,but still like to watch back to the basics videos just to keep kinda brushed up !!!! however, as far as the computer controlled voltage regulator, i've only really seen dodge to be the worst !!!! and of course most customers don't believe you and go some where else !!! after that ,....who knows what happened !!! thanks for your videos !!!!
That video was very helpful.Thanks
I am so happy I've found this channel. I love doing work on my own car and have been increasing my collection of mechanics tools. I recently just changed the valve cover gasket on my car which on a normal car wouldn't be that difficult but my car is a VW Scirocco 2.0 tsi and it doesn't even have a gasket. It uses anaerobic sealant. To get the valve cover off, the vacuum pump, hpfp, pcv and upper timing cover needed to come off. I'm watching every video you have made Eric and I hope you keep making them because there is nothing better than being able to fix your own car. Thank you so much for the time and effort you out into making these videos. Take care and stay dirty.
dude, i appreciate all your videos. you start with the basics, discuss theory of operation, cover variations and then work your way through a logical flow chart all the way to the end and then beat on things to not over look and then conclusion
Scotty you are main reason why I stop taking my car's to mechanics.Stuff that I thought was hard to fix you made it look easy.Just watching your videos did the trick. Thanks for all the videos.
his name is actually Eric
Tapping the alternator causes the brushes to temporarily make contact. One mechanic to another, Awesome video Eric.
You explain things very well,
Great video, Excellent troubleshooting flow chart. Thanks for the tip of checking differential voltage on positve/negative sides. as for oddsn'ends comment below: The author doesn't mention disconnecting your battery while running because this method if frowned upon with newer vehicles. That test can actually blow components. The battery acts as a filter cap and when your alternator spikes to 18v even for a nanosecond, you can potentialy destroy electronics because they operate at 12v with a small tolerance. You could get away 13, maybe even 14.5. It is dependant on the circuit and is risky even though it may seem to work. On older vehicles like mid 90's and below no problem. The test methods provided in this video may take an extra minute using a multimeter but it enables acurate diagnostics and less work. You don't need a socket to pull a terminal. That saves time. Thanks EricTheCarGuy!
Great video, Eric - always start with the simple reasons: corrosion on battery terminals, loose connections, loose belt. There it was - loose belt. $7 later alternator properly recharging battery.
man the connection issue is no joke! just went through two days of hell and may have killed another battery before i found a loose ground wire on the alternator. tightened all my connections last night. car started right up this morning. THANK YOU
Thanks for posting this video Eric! You've inspired me to learn about the Multimeter I've had for 10 years but haven't taken the time to educate myself about it, and how to diagnose my 2004 Santa Fe alternator/battery problem. Keep doing what you're doing ;)
Eric, y're my hero, had some problems with charging, removed the alternator, tested it inside - outside, shit could not find the problem, finally I decided to search your channel, and there it was, the mass cable between the engine block and the body was corroded, I had a voltage drop of 1,6 V with almost everything on and the engine running idle, it went to the roof when I turned up the rpm. Thanks man, you saved me a lot of money again.
One more test to do is to measure the AC voltage across the battery terminals while the car is running. It should be zero, but if it is higher it means a diode is no good and needs to be replaced. Great Video!
I haven't fixed the gauge yet, but I think that is the issue on an older truck that I have. Saved me about 40 dollars in parts and the grief of replacing those parts. Thanks Eric.
Your videos are always a great help. Thanks for dedicating so much time to make these. I run a lot of electronics in my vehicle and my Honda only maintains the battery voltage it doesn't really charge it. I also need a HO alternator and was curious if a self exciting one that constantly ran at 14.8v would damage anything?
I recently started doing as much work as possible on my own cars. Recently the battery light came on in one of our vehicles, I found this video, and solved the problem in just a few minutes. I was ready to go get a new alternator. After walking through all of the steps, I discovered that the belt just needed to be tightened.
Thanks!!! Your videos are consistently the best car videos I've seen around. Good solid advice and how-to's, with specific information such as what's shown in this video. I learn something everytime I watch one of these, and my wheels are still rollin'. Thanks a ton!!!
Big Help, Eric !..Did all these test for a low, weak crank this morning. 2 year old Interstate pricey battery. Charged the battery. Got all the right readings as per your instructions (even not above 60 degrees ambient). So...Hahahaha...Why the weak crank this morning. Car had been sitting for only 3 days. 28 degree nites. Hmmmm
This video just saved me from buying a new alternator. Turns out one of the wires had broken inside the socket so it wasn't that obvious at first glance. Thanks man!
Finally someone who really knows what they are talking about. Great video thank you
Eric. I have great respect for your diagnostic events. Working on a 2006 E250 Econoline 4.6L Van. The alternator gets very warm even with the engine not running. Engine cranks, won't fire. No spark, no Schrader valve found to check fuel pressure. Tried quick start but nothing of course.
Replaced Alternator (tested and found faulty) after it fried the battery and lights came on very bright in cabin. Truck finally died and was towed here. Rebuilt alternator is also very warm without engine ever running. New Computer NA. Thoughts?
🤷♂️
What was the issue?
My sons Exterra had a battery light on, with the car started was only getting 12.4 volts felt the terminals was very hot ! Turns out he just replaced the battery but had a loose connection! after cleaning and tightening it was charging at 14.3 v Thank you So much Eric I always tend to watch your Video's, Good content with out allot of fluff!
Great Video very informative. The only thing I saw for a recommendation is when Checking for voltage drop. You should set the meter to 2V not 20v, though in this case it would still pass. The meter should give you one one more digit of resolution in the 2V range.
Well Eric you saved the day. I had coolant issues with my 2001 Honda Civic. besides the cooling fan the thermostat was not working right.The thermostat was new. After watching your video on thermostats I found it was with that little value on the bottom. After the thermostat was put in THE RIGHT WAY all air was able to be removed.This isn't about alternators but thanks so much. By the way I have a 1956 firetruck that is positive ground. I had some charging problems. You videos have helped me out. Thanks.
please note also, and yeas ago, we chased this problem for a few days.
another thing to be aware of, is when you turn your key to the run position, the batter light should light up.
if the battery light is burned out, it will not trigger the Alternator (Voltage Regulator) to begin charging.
In the case f the vehicle we were chasing the problem on, My Boss, was "exciting" the Alternator At the field tab on the Alternator, And the car would begin to charge just fine till the car was shut off.
Shut the car, start it again, Not Charging!
Excite the Field, System charging until Car was shut off. WTH?
This was in the days before internet, So I went home and did a bunch f reading (from real books.....LOL).
It never really said "Hey, if the battery light is burned out, the car won't charge"
I had to "read between the lines" Went in next day, replaced Alternator/Battery light in the dash, Car started, and began to charge.
Outstanding comment, Thanks!
Great reminder about checking ALL connections first. Got a 99 civic ,and the alternator is BURRIED !!
Thanks Eric.
I would never take my car to a mechanic unless it's something I really couldn't do like transmission band adjustments or getting an alignment done. It just feels wrong to have someone else touch my car with out me being part of it
Lol.. I hear u. i often feel the same
@Edie Beacon look it up smart guy
George Clooney lol . I have only just found your channel, I have to thank you for taking the time to do so , I've just watched your battery drain video and im having the same problems with my KTM. I've found out I have a 5.5amp drain and pulled the fuse out of the solinoid and it goes to 0.00 so now at least I have some awnsers. Man I love you.! I fear my alternator has also gone .so here I am .
you're like my old shop teacher! but not drunk :) good job :)
Our shop teacher drank Listerine
Thanks so much, I had a flat battery this morning, changed it but was still worried about the alternator, but thanks to your video I've just tested it and found it to be absolutely fine! :)
I cleaned the bolts that hold my car's alternator, and my voltage increased around .4 volts, while running engine :)
Thanks for the excellent video Eric. It was very helpful. Mine turned out to be the fuseable link near the pos battery connection.
It was fried. Am assuming that one of it's functions was to provide exciter voltage to the alternator. Also great to find out
that the ecm could be controlling the alternator and that it can be bypassed in a pinch.
Hey Eric, first of all have to say mad respect brother. I've done many things and taught myself over the years and you have helped me a lot! Idk if you have ever worked on a Mazda tribute 3.0 or ford escape alternator. But I'm facing that soon and its no joke. Now before I do that ridiculous job I want to make sure it's not the ecu like u said. How can I test that? If I jump the car it shuts right off immediately. It is getting fuel bc it started. Battery is dead but I'll charge that up and test the alternator. But how do I check computer?
This truly is a great video. Nice refresher course for me, since I do do my own work, but not regularly, so I forget a few things, this video helped me refresh my knowledge. Thank you very much.
Very good instruction! Thank you Eric for taking the time in putting this together.
Eric, I would recommend starting the video with a highly detailed and thoroughly explained drawing that communicates what we're going to be doing in the video before we actually do it. Because of multiple shots and camera-off and camera-on, it's easy to get lost while viewing and not receive what you intended to give. I've watched this multiple times and am still confused. Thank you.
Thanks Eric!! You're very helpful in your comprehensive explanations. Helping me heaps at Mechanics school!!!
Thanks for videos. They have helped me when working on son's 98 4runner. I had an issue that seemed intermittent but was certain it was an alternator problem. Issue happened a couple of times again after checking all connections. First time testing alternator all tests passed. Performed again a few days later with diff test set and found diode test was failing. So, I got a rebuilt alternator from X part store. While testing in evening with lights on (eight miles after installing the alternator), radio and lights blinked. It blew the low beams. I installed the old alternator in parking lot so that I could get it home. I didnt want to take a chance on blowing high beams while trying to get home on new alternator. Took the new alternator to X where they tested new alternator - tested fine. It did not blow any fuses so I determined that it was not a high current issue but high voltage issue. X gave me another alternator and have had no problems. I still think it was a regulator issue with the 1st rebuilt alternator. Thoughts on supporting my theory. X would not replace my bulbs because of their alternator tests. Not happy because these bulbs are $25 for each. Thanks SteveBurke
Eric, Thank you for your excellent videos.. I have learned much, enough to keep my old car running... Job well done!
Best video I have seen on this topic.
My 2004 Expedition "Check Charging System" randomly beeps, when it rains. Then went crazy beeping for 4 hours on my last trip in the rain. So we had to turn the radio up to full, for our sanity. The next day no rain, no beeping. New battery, alternator tested fine. I suspect a wiring harness?
For diesel owners: If after starting the voltage is near or below battery voltage, the glow plugs may still be on. Glow plugs draw a lot of power and in some systems may be still be on for a minute or two after the engine is started. Either wait until the glow plugs shut off or disconnect the glow plug relay prior to starting.
Your video is still providing support, Thanks Eric!!!!
Great video. Very thorough. It looks like the positive side voltage drop part wasn't included though.
No, It WAS NOT.
I Ass-U-Me it is done the same as the negative.
It's not done the same as the negative. The positive side is tested between the positive battery terminal and the post on the back of the alternator, the one that was a wire bolted to it.
This point is stated in video.
Every sense I found Eric videos I enjoyed them and has helped me by watching them, Eric tells and shows right down what and how to, As a rating A+++!!
Manufactures do not make adequate ground for alternators. That is the problem. If they did, they would last longer and have more stable voltage. Bolting a alt to engine is NOT enough ground. Grounding alt body to chassis is better but still not enough. The only way to properly ground a alt to work optimally is to take apart alt and modify casing so that you can secure a 4gauge wire to the B- (negative side) of the rectifier bridge directly to the battery ground post. Do this and no more voltage/amp drops (assuming everything else is good).
Thank you for the help using the meter to check the alternator for charging, you are the man!
Hey Eric great video. Maybe i missed it but I only seen you do a resistance test on the the neg side but not on the pos side . You did mention where to test on the pos side do you use the same limits/scale on the pos side .1 to .2 volts resistance?
Yes one probe goes to +b on alternator
This guy paved the way! Bravo Eric The Car Guy!
working on cars.. voltage drop testing do you have a digital voltmeter..set it to 20 volts DC.
engine off.. headlights on for one minute. then turned off..
check battery voltage..
12.65 is a fully charged battery.
12.45 is a 3/4 charged battery.
12.25 is a 1/2 charged battery. if you have less than 12.5 volts have your battery charged and load tested..
once you verify that the battery is close to a full charge after you have removed the surface charge with the headlights on trick...
get the engine started... turn the headlights back on..
Negative battery post to the positive battery post.. 14.1 to 14.8 volts is expected..
Negative battery post to the engine block. 0.04 volts DC MAX..
Negative battery post to the body of the car.. 0.02 volts DC MAX.
Engine block to the Body.. 0.02 volts DC.
if you get more than the 0.04 or 0.02 volts on tests 2, 3 or 4.. you have a bad ground connection..
you can and should also.. after running the voltage drop test above..
test from the battery post to the alternator output terminal.. because of the amount of output.. i normally expect this to be up around 0.07 volts..
If u do have a bad ground connection how do u fix it? I have a honda civic 2015 and I just replaced the alternator and the battery and the cars battery connection light came up
You did a good job stressing the need to check connections. I'll take it a step further and say that when I have electrical issues I start by disconnecting the battery cables and cleaning the posts and terminals. Especially those side post batteries. They can hide corrosion at their connections. And unfortunately a voltage drop test won't show bad battery connections. Cheers.
never do the alternator test by removing negative cable on newer cars!!! or u will fuck something up. That shit worked fine with older cars but not today!
You neglected to mention a "slack" tensioner on the serpentine belt (if your car has one). These sometimes fail to maintain proper tension on the belt when the engine is operating. A "slick" belt can also allow inadequate friction between the belt and alternator pulley especially if the "back side" rather than the grooved side of the belt of the belt spins the alternator pulley. Wear causes the belt to become slick as if it were greased and can cause slippage. Check to see if some wires may have been chewed by a rodent or squirrel. Those animals are capable of chewing copper wires completely through. It happened on my Ford F350 Diesel when Mama squirrel built a nest under the hood and mothered 4 little babies in warm weather. I removed the nest and found that she had chewed an electrical wire completely in half when she built the nest. The engine would not even crank until I put the wire back together. Then it worked fine. The baby squirrels apparently have grown into adults and occupy trees around the house. No more trouble from them though.
.
I just had a check charging system and my battery light came wasn't too sure what to do thank you for making this video very helpful 😊
I've been a long time subscriber and I'm glad I decided to check your video before buying a new alternator! Saved me some money and time, only needed to clean the contacts!
Great thing about my 2006 Pontiac pursuit gt sedan... it tells you on the cluster when the alternator fails. 😊
so does my 1960 f100,but,non,tell you when the leads are corroded..which,is the main cause of dead car.lights,ect.
I'm going over videos today of you and Scotty as I figure out what's wrong with my 2000 Corolla. Alternator checks out for a load test, but the battery doesn't, and it's less than 2 years old. There's a lot of rust under the car, so I'm going to check my wiring connections and my grounds. Thanks for everything.
Eric this is phenomenal stuff! These videos are really great, and I'm learning so much! Keep them coming!
That’ll be $5000 please😁
Super great info much appreciated. I changed my terminals hoping it was it as the old ones were old N a tad corroded. The weather has been really cold after it started with a jump I failed to start for a few days so it was drained.
I went through all these tests because I couldn't find a parasitic draw. The truck sitting still and off was drawing about .84 amps with the key off. I pulled all the fuses one at a time, and didn't see an amp drop on any of them. When I checked from the battery to the alt casing, I got the .84 amps again. After checking and cleaning all my connections, I still have the .84 amp draw condition. But the alternator passed all the tests. Does this point to a bad diode within the alternator? The only other part I haven't checked is what appears to be a fuseable link in line from the alt running back to the dist. area. The truck runs and seems to charge the battery fine, but when it sits for more than a day, the battery is dead. Would this be caused by a bad diode? OR, should I go the extra mile and check my connections at the starter as well?
Interesting that in no comments asking for add'l info does Eric ever reply here... (Maybe on his web site) so all you'll get is other opinions from other people who also don't know how to fix similar problems... GRRRR...
Dude You are for certain THE MAN.. only wish You were My Mechanic.. Sooo hard as a Woman to trust any Car Mechanic.. years of bad experiences ruining my Cars..We Learn alot from Your Videos. You're a good Auto Instructor.
IF you START the video at 10:45 and end at 10:54 it appears as if the draw goes to .02 then .03 and you said that for this test it only registered .01. My question is not as a criticism but is it okay if instead it reading .01 it does read .03 would that be a unfavorable outcome? Perhaps you didn't notice the reading or it is not relevant? I'm just curious. Seems to contradict what you stated before.
.01 - .03 is completely different from what he meant which is .1 and above which means there's too much resistance on a wire... It can be a corroded or rusty ground/connection on battery or a slit on a wire/broken insulation causing not all the power to get to its destination like say battery ground terminal to the ground on the chassis/engine block
Yes 0.03 is great. He said the limit was 0.10 Volts not 0.01 Volts. A reading of 0.03 is one third of the limit. You're good to go.
Keep up the good work eric.One plint i should make that during alternator diagnosis qnd part of due diligence would be to set your meter to a/c volts and connect it to the neg and pos terminal of batt to see if any a/c voltage is present there.
That would indicate one or more bad diods leaking unrectified voltage.This usually results in low alternator output numbers during a high load test and can also manifest in battery going dead when vehicles sits over night.
+Mike Harris I was wondering why we weren't discussing AC ripple also but that usually impacts stereos and ground loops rather than poor charging situations in my experience. AC ripple shows up really well on a scope also. I think anything up to about .5V is pretty normal on some older vehicles...
5:00 You would not believe the amount of alternators I've fixed simply by checking the belt tension.
Samniss Arandeen if I am suspecting the alternator belt tension, (odd squeek at low RPM range and intermittent rough idle) could hooking up a 2nd battery (as if I were going to jump it, even though the car starts and runs), diagnose an alternator issue? If I connect a 2nd battery, it could smooth out the voltages, and if my idle issue goes away, then I know its power related?
Samniss Arandeen if I am suspecting the alternator belt tension, (odd squeek at low RPM range and intermittent rough idle) could hooking up a 2nd battery (as if I were going to jump it, even though the car starts and runs), diagnose an alternator issue? If I connect a 2nd battery, it could smooth out the voltages, and if my idle issue goes away, then I know its power related?
Ultrajamz I've never done that particular test. Usually I just check belt tension during the visual check of the alternator itself.
+Samniss Arandeen you wouldn't believe how many people falsely believe that by tightening their alternator belt, they'll fix an alternator problem...all they usually do is overtighten the belt, and burn out the alternator bearings..so yeah, 99.9999% of the time it is not belt tension...
can an alternator still be bad if you pull out the cable and it runs the positive cable
im in a car mechanic class and i got a big exam tomorrow, you probably just saved my ass, thanks. :)
Eric you are very thorough thank you
Oldie but a good one. Nine years is a long time and you only got better
Excellent video, very informative!!
This was a great video. I was going to replace my alternator, but now learning that you want to be .5 above the battery condition has me thinking twice. I have done a peristaltic test, I do have an isolator in my truck, same batteries, Interstate, same age. Took the truck to Good year, they ran the test, everything came up clean, but still battery dies after 3/4 days.
i love that little motto of yours....."stay dirty"......
hey my battery does not charge..got the alternator checked..no problems there..what else can i check ?
Dane Montague Uh, the battery.
Dane Montague Jup take a multimeter and start checking it
Bbb industries is my goto for ALL my wiring diagrams and tsb info ! Thank you guys for that info and to eric for your guidance on many things!!!
They don't do those anymore.
@@cward1954 yeah I recently found that out its a bummer cause I loved that site. I wish they would give reasons why or where 1 can go to find them
This video was awesome. Thank you so much Eric!
Man I remember when I first saw eric the car guy and he only had like 40000 subscribers now he has half a million good job eric I knew you would blow up one day
AJduong333 how about now! Lol
You had me at "stay dirty"
Older volvo bosch alternators are notorious for won out brushes. And they're cheap & easy to replace. Full fielding is a very handy test! And ground straps can get corroded on all cars. A continuity check from alt case to batt neg terminal takes a few seconds, and finds problems fast. Then polarizing old generators... Just googe it. lol. great vid!
My voltage needle bounces when I turn on my headlights I did the drop-down test and it seems fine, any ideas?
replace your Serpentine tensioner + belt if above 80kMi
Check your ground on the small wire on the batt
I had a Nissan Pathfinder that when running, would actually blow out the headlight and the heater motor sounded like a roots supercharger! This vehicle had a separate wire from the alternator to the battery post where the plastic connector corroded and failed so the majority of the charging was going right back into the car's electrical system and not the battery. The dealer wanted to change the entire engine bay wiring loom to which I told them to pound sand. A local car electric shop changed out the connector for $20.
I also had a 1991 Camaro that wouldn't hold a charge so checked the usual suspects like you mentioned but couldn't find an obvious fault. This car didn't have a wire from the alternator to the battery but the positive battery cable had a mid point junction for the charging and accessories so in the end, had to change out the factory battery cable which was not cheap.
can you do a video on overcharging my 2007 ford five hundred randomly puts out 19.5v
That's what mine is doing. I've blown thru 2 brand new batteries and 2 regulators, in the same day! I have a 1990 Ford van. With a 5.8 liter engine. Someone told me today that I should sell it for parts. So frustrating.
@@adelemartinez8235 have you fixed it?
@@adelemartinez8235 have you fixed it?
Have you fixed it?
@@johnmurner2418 no. I haven't. It sits outside still.
The first suspect is always the Battery, many auto parts stores now do load test on batterys for free to see if your battery is holding a charge. If the battery is ok, then proceed.
Get a Volt meter that has aligator clips, disconnect the positive cable from the battery, leaving the negative cable connected to the battery. Hook the Positive or red cable lead from your Volt meter to the positive terminal on the battery and hook the Negative or Black cable lead from your Volt meter to the positive cable, makeing sure that the positive cable ends do not touch ground. With the ignition off, the Volt meter should be reading 0 volts, but if something is shorted or staying on, you will get a 12 Volt reading. Assumeing that you have a voltage reading, its now time to proceed to the next step. Completely disconnect the wires from the Alternator, keeping the wires from touching ground, and see IF the Voltage reading drops to zero, if it does, your Alternator has a shorted diode, the alternator will need to be replaced (common problem on S10 models) If the volt meter however remains unchanged, reconnect the wires to the alternator. The next step have someone watch your volt meter as you beguin to pull the fuses from the fuse box, if the volt meter drops to zero after pulling a fuse, it will give you an idea of what circuit is shorted, their by drawing electricity, while the ignition is off. Get a Chiltons Manual on your make and model, and look at the wiring schematics for that particular circuit..
Is this true? I Put a new Alt. on the trucj and still showed a 11.8v drain?
Great stuff, thank you Eric.
Thank you for sharing this video. I appreciate all of your hard work and time, in making these videos.
Hahaha man. you look like Geroge Clooney. thanks for the tips brother. great job!
Nice video, a good linkable follow up would be a "mythbusters" of how NOT to diagnose an alternator, like "start car then disconnect positive terminal and see if car dies". etc.
+Snap-off - Go to Harbor Freight and get a *PLUG IN Battery/Alternator Tester* for $6.99 and NEVER have to worry about it again! YES... You will know ALL THAT 24/7 or when your Battery is not charging or Alternator is dead, etc... !!!
Thanks for the reply. I have a multi-meter and a college degree in electronics engineering, so I'm good on alternator testing, but I'll still check them out because little electronic devices like that fascinate me and are why I got into electronics engineering in the first place!
My car won't start at all. The last time I got it started I noticed that the alternator wire was smoking. I believe this is the reason that my battery died. What can I do about this and could you give me a reason as to why this might be happening?
Hi Dell M, I have the same exact problem. Did you figure out what went wrong? Thanks. saadak@gmail.com.
Thank you Eric,you made it more understandable for me to wrap my head around my problem with my 1984 toyota camper that's on the 3rd alternator voltage problem/parking lights/volt light on !
And this is how i learned that my alternator is a POS
I have to say what a Great video walking thru voltage drops and how to go threw a proper charging system and how to rule out other areas. I have a 2007 Dodge Ram 2500 5.7 L Hemi I have replaced the ECM Module and Starter a year ago. My Mechanic had my truck for a week he does a great job but I work for myself and dont alway have the money. I am having the same issue i had a year ago, I was coming home from a job and notice the battery discharging negatively and it got worse as the day went my alternator had a bearing hum replaced it and still having issues ALternator was not the issue but the bearing was showing wear.
I know alot about motors and engines but I dont know everything
Im a utility engineer and Im knowledgeable. This Video Made my battery and ECm and charging system easy to understand .
Thank you for the Education......
u get any sleep man..take a vacation. u very infoemative. thanks.
Great video. It refreshes the small things a person may not think of. I hate those new smart charge systems where the charging is controlled by the ecu
9:43 What happened to the positive side check?
should be same idea, pretty simple. positive side on alt to positive terminal.
han nguyen
Thanks, Han, but I would not guess with something like this. It would be a shame to fry an alternator doing the check the wrong way.
acoow When doing the test on the positive side you touch the pos lead of DMM to pos on alt and neg lead to pos on battery, this will not hurt anything. in a nice DMM if something goes wrong theres a circuit breaker inside of DMM that will break before damage to car occurs. Im a certified diesel tech.
BassheadGTP Is this with the car running also? Can it be done with the car engine off, or even with the alternator disconnected? I mean, testing between the battery's positive terminal and the alternator's connector. I ask because it's impossible to get at the alternator's connector when it's mounted.
@@BassheadGTPwhat should the acceptable reading be please?
Once again another outstanding video. I will do some more troubleshooting on the Honda (battery and door light stays on until I rev up the engine to 2000-2500 rpm).
Your video covers everything. Great!
I like do work in my 2004 Sierra SLE ext. cab 5.3L V8. I just got a new battery and now in the cold morning when starting the truck a warning sign comes up, "Battery not charging" and voltage drops to 9V this lasts for 20min till engine warms up, then voltage goes up to 14V. Is that a sign a have a bad alternator?
Thanks!
Edson Colle
My 02 Sierra has been doing the same thing. Was yours the alternator?
EricTheCarGuy you should do a separate video sometime checking A/C voltage coming from either the battery or alternator (or excessive ripple) that can be caused by a bad stater or diode in the alternator, or a bad battery.