basic voltage drop testing for automotive electrical testing
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- Опубликовано: 5 июн 2024
- How to use your meter to measure voltage drop in a automotive electrical circuit. I do diagnostic jobs for many repair shops in my area, and one thing I see all the time is the misdiagnosis of circuits and parts " hung" that do not fix anything all due to improper testing.
Equipment that I use:
TopDon Battery Maintainer amzn.to/40mubUw
Cardaq Plus 3 amzn.to/3Z9F3V1
Astro Meter amzn.to/402cIkJ
Quality Test Leads www.aeswave.com/Automotive-Te...
amzn.to/3LH5Vsc Pico 2205
Camera equipment that I use in the field
amzn.to/40jzpR2 - Sony ZV-1 Camera
amzn.to/40hchCA - Tascam Audio Recorder
Studio Camera amzn.to/3Jz7A0p 
Авто/Мото
Helpful video. I'm struggling with electrical and this video made it simple to follow. Again, your simple mock up is the best way to do electrical videos.
Voltage drop has been a diagnostic mystery to me. This video helped a great deal in understanding the principle of the test. Thank you.
You must try FD Automotriz. Clear, good explication. In espanish.
Excellent, now I understand. . Especially liked the recap...they are an important part of instruction, but are often overlooked. Camera work didn't interfere with my understanding. Thanks for the time and effort here.
THANKS BRIAN , voltage drop testing is one of the greatest fundamentals !
Great Video! Really shows voltage drop along your ground bar! Thanks so much!
Thanks for showing how to do voltage drop testing.
Good job.
This is a good video. You didn't need to worry if the drawing was hokey. Anybody worth their salt will understand it. Abbreviations can throw a listener. I wondered if the EMT rail was the emergency medical technicians rail. Very nice. Thankyou!!
One of the better videos on electrical testing ... very clear instructions. Thanks for tour tips.
try the six parts of this test also.. the first 4 parts can be done in under a minute on any vehicle
here is a voltage drop test you should also teach ..
engine off. turn headlights on for one minute. then turn off. set volt meter at 20 volts DC. measure battery voltage at the posts..
12.65 is a fully charged battery
12.45 is a 3/4 charged battery
12.25 is a 1/2 charged battery.
try to perform this test if the state of charge is over 12.5 volts.
start engine . turn on headlights. meter set at 20 volts scale.
test One. Negative battery post to the Positive battery post.. 14.1 to 14.8 volts DC is expected.
test Two.. Negative battery post to the engine block.. 0.04 volts DC max.
test Three. Negative battery post to the body.. 0.02 volts DC max.
test Four. Engine block to the Firewall . 0.02 volts DC max.
test Five. Positive battery post to multiple fuses in the under hood fuse block. 0.04 volts DC max. try to test as many fuses as you can.. there are multiple buss bars in some under hood fuse blocks and you can loose individual sections.
test six. Positive battery post to the Alternator output stud. 0.3 volts MAX that is 3/10ths of a volt.. because the alternator is putting out significant current. i like to see as close to zero as possible.. 0.08 would be very good.. 60s and 70s mopars with hard wired amp meters in the instrument cluster will read 0.7 volts and be perfect.
if you get 0.00 on tests two thru 6.. change the volt meter setting to 2 volts DC or 2,000 Millivolts DC. perform the tests again.. some meters don't show fractions of a volt below 2 volts very well. a test section showing 0.00 volts usually is an incorrect probe location for that section of the test.
tests 1 thru 4 should be performed on every car with any kind of electrical issues. including engine /codes. 1 thru 4 can be performed in under a minute after you have learned them..
you will want to perform tests 1 thru 4 and perhaps 5 on every car before you finish working on it to prove the wiring under the hood is properly hooked up. you cannot see voltage drops except with this test. it will save your hours of work and also prevent many comebacks if you spend these few minutes and PROVE the wires are properly attached and not corroded.
Thank you for the information, you definitely have some quick test to weed out simple voltage drop problems quickly!
Great video. Makes you understand and see voltage drop testing in a simple clear way. Thanks
Thank you Brian, your video really clarifies the concept of voltage drop.
I’m really sad.. see I saw this video and I thought it couldn’t teach me anything.. desperate to see if I understood voltagebdrop.. I watched this randomly all the way through and your ending hit was the BEST INFORMATION I’ve heard after studying voltage drop for about 4 days now.. “the ground from the battery is the best to use for voltage drops. I’ve been burned when I thought I had a good ground and it skewed my results and it was a waste of time...”
Wow. Going to watch this over and over- I think this is the most in-depth tutorial. Your art work is perfect lol for someone like me.. because when you mentioned the connection splices I started to understand what you meant with the resistor acting as the load as the current “flows through”.
Great work on the resistor. I was thinking what kind of dopey test is this.. I can guess it.. bu NOPE you made me think. I also like how your switch and headlight were an actual headlight and not just a bulb.
You can really see you have a great way to teach, thank you for recommending the jump point after and before the resistor for the bulb to light- I think I finally understood voltage drop after that. God bless!!
Really good. You should do more! You explain very well
Maybe camera tripod
Sure you would do well! Please do that! Other sites miss a lot.yoi are much better at teaching.great opportunity for you and watchers wanting to learn this subject.
Thanks for the compliment and comments. I do have membership site that goes deep into basic electricity and voltage drop testing, along with pico scope and other videos that are not on RUclips, its 10 bucks a month , courses.handsonautotraining.com/
this really helped me understand voltage drop! thank you
EXCELLENT. So clear seeing it on your rig. Thanks.
Just like the old water hose example. Great lesson for new-be's... Thanks!
damn bro... ty so much...it helped me a lot.. dummy prove...u r a good instructor!!
explained brilliantly, thanks.
I am working on making a video on voltage drop. This has been a great tool for me since the mid 1970's. It is a way to indicate decreased current flow in a circuit due to resistance. The higher voltage drop in a circuit indicates that less current is flowing in the circuit causing that circuit not to operate efficiently. The best example is a tail light circuit in an older car. You notice they're not as bright as they were than when they were new. Measure the voltage drop you will probably get over a 1 volt drop or difference. It is important that when using voltage drop in a circuit that the circuit is operating under a load.
Thanks for making the effort to do the video. Knowing a subject well is not always a good indicator of the ability to explain that subject. I had to view your video four or five times, and I am still not sure what you intended me to learn. I did, however, learn some things. So, thanks again.
Ian Simpson hi
THATS A GREAT VIDEO , SOMETHING YOU WOULD ENCOUNTER ON REAL LIFE.
Thanks for the voltage drop video. Very good informative video. Also good info in the reply section. ❤️
Great Video mate , Top stuff.
Excellent video on voltage drop testing.
Great video. When you gather enough experience in electrical diagnostics you learn when to use a multimeter or a test light. On this case using a test light would be the best approach wether you front probed (circuit unloaded) or backprobed (circuit loaded) you would have seen the voltage in the brightness of the light.
Very informative. Thank you.
Excellent video.Thanks for sharing
Very good demo. No video is better.
great video all I need now is practice
Great Video...please keep them coming
P.S. no more getting us DIZZY😀👍👍👍👍
Thanks for sharing!
More videos! Nice set-up...
Opinions vary regarding this topic. But Brian does onsite electrical diagnostics and computer reprogramming. With that said I would say he has a good handle on how to do electrical diagnostics.
Nice job I read the comments boohoo you get the point of what he's trying to say good job keep it up
Great video. Another way to say it is, the circuit must be "loaded", (ie drawing current") for the voltage to drop across the circuit.
Hi Brian thanks for your video .I have a question what is your taughts on converting a alternator with internal voltage regulator to external regulator?
great job..thanks
Nice setup and display you have there.
Would it help to do an Amp test?
How would you measure Amps on that setup there?
Great Video Brian !
Thanks for watching!
got me dizzy but helped a lot thanks!
Great Video!
Thanks, as I am sure you can see this video was made a while ago.. Do you think ther would be a interst in an updated version / or is this one pretty good?
Good video!
LOADpro it, or just attach a 25ohm resistor to the end of the red lead when it's unplugged.
Great info and your setup was quite helpful. One thing that would have helped even more is to have someone help shoot your videos. Not a huge distraction but would make your vids that much better. Thanks again for the very helpful info.
very helpful video bud
I have a 03 Escalade my taillights running lights at night sometimes they do turn on and other times were they don’t turn on but my turn signal, reversed, brake light do work my headlights work except if I put the parking light nothing happens
good job
the swimming video is fascinating.
Great info. But you need a 3rd hand for the camera.
But very informative great great info
very interesting video
all depends of what system voltage says. test through fuse block. ghost v = open 00.00v = open v drop= high resistance
Awesome
If you are interested in a more detailed basic electricity course please check this out.. courses.handsonautotraining.com/courses/essential-electricity-for-automotive-technicians
Very easy to understand .I like the way you set up a test rig for the explanation which helps quite a lot.Thank you.Also will agree with Bonfield2002 .Check out loadpro for really quick and easy voltdrop testing with the use of loadpro connected to you own multi meter.
For everyone here is my situation. I have a low voltage of 9.5v. On the IACV (iddle air control valve) from my 97 maxima. It supposed to be 12v. Do you guys thing that ecm/ecu will be the reason or just a short somewhere?
I pulled code p0505. Any experts in here?
is this test applicable to crank sensor or camshaft sensor testing? thank you.
Fantastic,well done !! I agree with everything you said, I do have a slight twist on voltage drop testing that does include disconnecting the connector from the bulb. I use specialized test leads attached to my meter and never take them off called "Loadpro". Google them from Sullivan electric sold thru AESwave.com. found them on youtube Saves me lots of time and the best $60 spent in a long time.
you can even isolate which side of the circuit the resistance is on
Try FD Automotriz. Is very precise, clear.
So the reason we see voltage when the connector was unplugged is because without current flow there is no resistance provided by the resistor and hence no voltage drop? You would think the resistor would change the voltage at least a bit but strangely it doesn't. Thanks
its because a multimeter has a very high input resistance, thus it will read the same volts even at the end of a pretty high resistance, the common 12v light bulb tester is in some ways a better tester than a multimeter
good demo.could you please demo load testing a circuit?
Sorry for overlooking comment, Load testing would be "loading " the circuit with the same load / or amperage draw as the circuit would encounter during normal operation, so if you have a component that is operating properly, back probing the powers and grounds to that circuit measuring the voltage drop is load testing the circuit. using a old fashioned sealed beam like in this video is goo for load testing a circuit to about 5 amps if I remember correctly. If I have some time i will make another video explaining better.
the failed resistor isn't indicated on the diagram; it might help to know it's there
I am really trying to understand voltage drop and watching videos. I really do not understand why you are getting 12 volts when front probing the connector disconnected. Say you test a connector from a source that goes to a sensor unplugged and do not get the voltage you should. You would then look at the wire from the that connector to the source. Usually it is open or it has resistance. You had a resistor in that wire you tested when unplugged and got 12 volts. Can you explain why is that. I do not understand.
it shows 12v due to the fact that current is not flowing, the meter alone does not pull any current.
the battery voltage is the potential circuit voltage and that is what the meter is showing.
You only see that resistance when the load (lights) is on. (Switch turned on).
but will it blend?
Put out timing videos on 3.6 and 2.2 please. Detailed
I will see what I can come up with..
By yourself a loadpro and you'll save all that time doing those test.
Good Info but Camera handling made it hard to watch.
Great video Brian. I'm in agreement on the loadpro leads. A awesome tool. Check out the tst roundtable discussion for february on youtube. They interview Dan Sullivan, a electrical trainer an the inventor of the loadpro. Check it out.
I feel dizzy from the appalling camera work, please get a tripod or helper. Video had some interesting information.
U need a camera man
WHY ARE ALL OF THESE "HOW TO MEASURE VOLTAGE DROP" VIDEOS MORE THAN 10 MINUTES.... GHAGHAWIFOEFIOJ CANT BE THAT HARD
THANK YOU It's sooo annoying I just want to learn something simple! But nnoo I got to deal with all this 10 minuet + crap
At 0:48 I feel like the acid just kicked in.... Why is my vision distorting?
you need a camera man really bad
Try a Loadpro. Watch YT videos by Dan Sullivan.
Your making it to hard just use a light probe or a circuit tester that would put
a 12 to 14 watt load on the line as you test it.
Too messy, camera zips to fast back and forth often the probes are out of the picture. Difficult to follow . Where is the black probe ?
I appreciate your intentions, but this was spoiled by dreadful camera work, it made it a real labour to watch.
Huangango
Your camera is on shrooms... LOL
PLEASE - Find a camera man!!! Great video, but filming really sucks
Marcusspain1957
get a director
There is no ground in an automotive electrical system.
+jim davidson what are all the grounds built into the car for then e_e
They are negative terminal connections. Remember on the battery? You have + and -?
+jim davidson yes there is!! what is the black lead for? disconnect the black the starter does not work. i guess its all positive leads..
Grounds go to Earth. The thing you walk on. Negative terminals or connections go to the negative side of the battery. See, wasn't hard at all.
chassis is ground
i see your explanation, but this is the worst video ive seen/i was dizzy in the first min.fix the cam position and stop holding the cam