Personally, I always used a headlight bulb to put a good load test on the circuit. Learned that the hard way at the GM training center. That's when I learned the difference between static and dynamic testing. Some of the best knowledge I got was from there. Always do a voltage drop test with the meter, in conjunction with the headlight bulb.
Seeing these concepts in the field for the first is definitely crazy lol, when I started really doing voltage drop tests and understanding how and why they work was awesome. It never clicked till I started watching your videos so thank you. It really hit home when I got done watching your videos the one night just so happened had a now start issue on a boat motor and I applied what you are talking about now and saw it like instantly. Grant it I was lucky where I started but still seeing it and going holy shit I have a bad ground and now was looking for and found. My god it was a fantastic moment since I knew I had learn this but also it was sick seeing it all happen and how it did. It was so cool making it have voltage and not have voltage on the ground by simply tapping and untapping a broken wire on a ground bundle. lol I’ll never forget that day and how it all made sense. SO THANK YOU DANNER!! Anyone and everyone I meet who is thinking about getting into this field I tell them go watch you or if they are in the field I tell go watch you. I have learned so much.
Went through a bit of a similar situation with my friends 1995 Dodge 2500 truck last week, It has a bad connection with the main battery ground connection at the engine block, The engine still cranked over and started, But it was pulling excessive amperage through the body ground strap between the firewall on the rear of the driver side cylinder head, and overheated the ground strap so bad that it melted the coating off of it. Thank you for another great video Paul.
Your career experience is solid information and I love practical remarks like that. In the AC world it is not uncommon for motors to die as a result of voltage drop in the supply line, although I don't know about DC automotive fuel pumps. It took me a while to understand why for example an AC well pump might die as a result of inadequate voltage from upstream or downstream electrical line resistance. When AC motors get inadequate voltage, they respond with the only thing they can do, demand more current to build enough power to overcome startup torque. That higher current for longer time leads to the tiny wires inside the windings getting hot and the motor burns up after that. To make things worse, the duty cycle of a motor getting inadequate voltage makes it work even harder for a longer time to meet demand. So, wise electricians may do a quick check of voltage at the new pump when it is working to reduce the chance of damage to the new pump. I hear you when you say that high current light bulbs aren't necessary for automotive diagnostics, but it is so easy to do that check, so why not?
I've studied this strange phenomenon. Not sure the difference with the AC and DC motors offhand, but this explanation makes sense: low voltage to a motor, equals less counter emf (counter voltage) the motor will produce because it is spinning slower. This is what limits current flow. The slower the motor spins, the higher the amperage. There are variables to this of course. But I've not seen a burned up brush type DC motor with the cause being a low power feed or good ground. I would say that if I had repeated motor failures on a circuit, I'd definitely be testing the power and ground with a little more scrutiny. But I don't fault those who like to add additional loads. I just trust my meter and my test light results, so never had the need to go beyond these two tools.
Thank you for all you do for us, Paul! I’ve made a few “noid lights” with various bulbs with wire leads and small T-pins to plug into circuits to load test, I usually use one that has a 9006 halogen bulb. In my earlier days, have been fooled a few times with a volt meter before I understood that a circuit needed to be loaded..
If the horn was good and the wires couldn't support the current flow you would see it with your meter or light as voltage drop. Thanks for all you do Paul.. 👍👍
Yes most awaited video of the week😍😍😍 Thanks for sharing SD👍🏻👍🏻👍🏻 Please share some latest case studies with James Danner😍😍😍 Always an honor, Stay Blessed Danner Family🙏🏻🙏🏻🙏🏻
I had a lesson in AC voltage on a heater. All my safeties tested good on resistance but no heat from 240 vac heater. Rigged up test live and tested each side of the safeties and on one I was getting 240 vac which told me the safety I was testing was bad because I was getting 120 volts from l1 and 120 volts on l2 that went through the heater to my safety. Now I get the phrase electricity follows the path of least resistance because if the safety was good then the heater would've gotten the 240 volts instead of the safety.
You have isolated the component in question This is where I would Continuity test across the horn input leads No Continuity means - Blown Open Coil "No Need to Go any Farther" (The Harder it has to work the more power it needs to do the work, It Becomes Exponential) That much draw comes with that much heat Heat and Current find the weakest Point & Pop, you're out of commission But You're Teaching Voltage Drops... In the vehicle it would be part of a system There you would be best measuring Voltage draw in action Good Show Thx Paul Side Note My New Fuel pump that's not pumping, did not prime using external pump, or vacuum pump Tanks coming out! After some rest and healing, I'm ready to do it Again lol
@@ScannerDanner Pulled it, tested functionality in a cup of gas - Tested Okay (Pump Works, that's not the problem) The pump filter was flat on the bottom of the tank, I rotated it up, put it back in after readjusted the filter screen Added Power to the contacts pump put 40 lbs onto the pressure gauge - Tested Okay Vehicle Starts & Runs Conclusion: (I'd say the screen sitting against the tank bottom, eliminated it's ability to draw gas into itself ("Plugged it") I'm Taking Er Off the Blocks The Worst Job is Now Done! "Next!" lol thx Paul
Shows how to diagnose properly then shows his Jeep on fire haha, just joking, I've been following you for a long time and you definitely know your stuff. I enjoy the videos and thanks for sharing your knowledge.
Man, that jeep....I'm still shaking my head. All that was done was a student did the valve cover gasket BUT, I blew chunks of heavy carbon out of the top of that engine to clear out the drain back holes (300k with crap oil change maintenance) My theory. A chunk of that carbon landed on the exhaust manifold and didn't catch fire until I stopped to get coffee. It then lit and burned right below the main harness and fuel rail.
Horn quick test when connected like that is hit the back with a big spanner. Most likely it will make some sort of noise for a while, fixing the worn internal contact. Same for a failing fuel pump, a bit of percussive maintenance will get it to run possibly, till those brushes fully fail, or the commutator finally burns out.
I also use Load Pro leads on a DVM, you can load the circuit with 500 ohms and confirm and resistance of the wiring is ok on both sides before the pump/horn etc.
Both methods have their merits; a DMM provides a more qualitative measure, whereas the test light provides some load. I wouldn't like to say which method is "Best" as always it pertains to the circuit in question. What's probability more important is knowing your circuit design and the limitations/variables of any tests you plan on making. More importantly as Paul said, testing under load is vital and the consumer provides that "Load." I used to test with various load test lights before i properly understood Voltage drop, but hardly ever do so these days. A more advanced progression of your diagnostic skills, is to understand the "Most likely" the root cause of failure, and not get caught up with obscure possibilities that almost never occur. I struggle/d with this for the longest time, and tend to always keep myself in check by asking myself the most likely root cause and parking anything else untill necessary.
Thanks to Paul for some great testing of indicator lights. Now I'm looking through your playlists on RUclips, chapters 17,18,19. The first videos in the playlist were filmed 10-11 years ago, you have a pilot lamp in the shape of a screwdriver, it would be interesting to know how long it worked for you, and are there pilot lamps on sale now in 🇺🇲? I recently saw such a lamp on a Chinese 🇨🇳 website. Oooh, this is the lamp that S⚡D had Thank you very much for sharing tutorial videos on RUclips 👨🏼🔧....
Great video, I was wondering if you could make a similar video showing how to use your test light to power something on. I’ve seen you do it multiple times but still not 100% on how you know when it’s going to activate the component your testing.
Use a voltmeter. There is really no need to use a test light to test a 5v ref circuit. In some circumstances you can, but you need to know what you are doing and most certainly know the current draw of your test light
I've been in a nightmare trying to help a friend on their 2008 gmc 1500 5.3. DTC showing no communication with TCM, no oil pressure reading at gauge, windows acting up. Testing at DLC, have 60 ohms on pins 6 and 14, Testing low speed bus splice pack under the dash, I'm averaging around 4.5v but every few seconds 11.2v is spiking for split second. It shows up as soon as the key is in accesory, plus run. It only happens on pin M once all other pins are isolated. Pin M goes to the BCM. Only way I've gotten it to go away is either pulling the DLIS 2 amp fuse, unplugging the ignition switch, or unplugging the X1 connector at the BCM. We've cleaned almost all grounds and checked most power connections. We've unplugged just about every module on low speed can bus, the spike stays on until the BCM goes to sleep. It almost seems like there's something going wrong inside the BCM circuit board. It spikes 11.2v every 3 to 5 seconds, then bk to 4.5v. Its been a nightmare lol.
What is the voltage range of the low speed bus you are testing? Is it a single or two wire bus? You really need a labscope to look at network signals. Relying on an average voltmeter reading is difficult
I also feel like they both work as long as you understand the fundamentals of this test. But it’s more about people one guy is a numbers guy and one guy is just seeing if it works. I’m the numbers guy lol
So, maybe I missed it, but how does the meter show 12 volts at ground (17 minutes in) when the ground wire is open? Don't you need the positive side and the ground side to light it up? Ground to ground should not make it illuminate. Shouldn't that be a short? Where am I wrong?
He's trying to show what happens when checking an energized circuit with an open ground. The electricity flows through the resistor, then through one of the wires of the little motor into the little motor, but since the other wire from the little motor is not connected to ground, the motor doesn't run because the circuit is still open (not complete). You should read a book or watch some videos on basic electricity before watching videos similar to this. If you don't, it's going to confuse you and hinder your learning. Even better, grab a couple of light bulbs, some wires, a battery, and a voltmeter. Connect them in series and check them with test light and voltmeter. Then connect them in parallel and check with light and voltmeter. Check before and after every light and make note of the light and meter readings. This is basic. It's like adding 2 plus 2 in math and I'm not exagerating.
You are not wrong that a short to power on the ground side of a basic motor circuit could also cause the test light to illuminate. The next step would be to unplug the load (horn) and retest the ground circuit on the vehicle harness side. If the test light still illuminates, or meter still measures voltage on the ground circuit then this suggests a short to power condition on the ground circuit to the motor. A common cause for this that I have found is a bent pin in a harness connection. The ground circuit pin bent and touching a nearby power circuit pin. A less common condition than a failed horn or motor but still a valid question you presented.
@@wayneschirmeriii6487 A short to power on the ground side of one circuit is a short to ground on another circuit. This is not what Paul is showing at around 17 minutes of the video and that's what the question was. Paul is showing an open ground.
Since there is not a complete circuit. You will measure the voltage through the load. That’s why the meter reads 12V with an open ground. If the circuit was operating correctly. The meter would read close to zero which would indicate a good ground.
No current flow, equals no voltage drop. Power comes into the positive side of that motor and comes out the negative side "looking for a ground". A voltmeter will show 12v (same as the source) regardless of the resistance of the output. Let's compare 1 ohm (electric motor) to 150 ohms (relay coil) for this example. Both circuits will show the same 12v with an open ground when using a voltmeter (no current flow, no voltage drop). Now, let's use my test light. Remember that connecting this light, in this way, with an open ground, is basically putting another resistor in series after the load. The 1ohm circuit will have very little drop in voltage, so my test light will be very bright. The 150ohm circuit will have a large drop in voltage and my light will be very dim. There are variables within this test too, and one of them is my test light itself! The light I'm using draws about 200ma. To put this another way. The motor I'm testing probably carries 3-4 amps and my test light can only carry 200ma, that is why the ground wire is so bright. If this was a relay coil that draws less than 100ma, my test light would have no problem energizing that circuit (at least partially anyway) and the bulb would be very dim in that test as most of the voltage dropped across the first resistor. Lol. Now I'm rambling. Lastly, you will never troubleshoot a short to power on a ground wire. Why? Because you would attack that problem as a short to ground on a blown fuse or possibly a blown out computer driver on a power side switched circuit. But even with that, you're testing the power feed wire for a short to ground. Never the other way around. At least in your head anyway.
What's up with all the female bots leaving comments? You know most of these women (probably men) aren't interested in videos like this. Even some of their comments don't make sense or relate to the video. I haven't seen this on other RUclips videos.
When the output is static, it's just a wire. For all those who would bust out the scope for this, you're wasting time. A scope is a good tool, but it is unnecessary for simple testing.
![Voltage Drop Testing with a Test Light? [Part 1]](http://i.ytimg.com/vi/kTW68s5vqIg/mqdefault.jpg)
![Voltage Drop Testing with a Test Light? [Part 1]](/img/tr.png)
Personally, I always used a headlight bulb to put a good load test on the circuit. Learned that the hard way at the GM training center. That's when I learned the difference between static and dynamic testing. Some of the best knowledge I got was from there. Always do a voltage drop test with the meter, in conjunction with the headlight bulb.
I have used this test many times, I modified it a lil by using my meter with my test light to get a voltage reading, excellent test.
Beating a dead horse? It doesn't matter how you explain it some people just won't get it. Very good content. Keep the kiss method.
You really give me confidence to do electric work
Awesome! That is great to hear
It's always good to have a refresher. Thanks Paul.
Seeing these concepts in the field for the first is definitely crazy lol, when I started really doing voltage drop tests and understanding how and why they work was awesome. It never clicked till I started watching your videos so thank you. It really hit home when I got done watching your videos the one night just so happened had a now start issue on a boat motor and I applied what you are talking about now and saw it like instantly. Grant it I was lucky where I started but still seeing it and going holy shit I have a bad ground and now was looking for and found. My god it was a fantastic moment since I knew I had learn this but also it was sick seeing it all happen and how it did. It was so cool making it have voltage and not have voltage on the ground by simply tapping and untapping a broken wire on a ground bundle. lol I’ll never forget that day and how it all made sense. SO THANK YOU DANNER!! Anyone and everyone I meet who is thinking about getting into this field I tell them go watch you or if they are in the field I tell go watch you. I have learned so much.
Fantastic moment indeed! And one you can visualize and fall back on to help you with other similar issues. Good stuff man, thanks for sharing!
Went through a bit of a similar situation with my friends 1995 Dodge 2500 truck last week,
It has a bad connection with the main battery ground connection at the engine block,
The engine still cranked over and started, But it was pulling excessive amperage through the body ground strap between the firewall on the rear of the driver side cylinder head, and overheated the ground strap so bad that it melted the coating off of it.
Thank you for another great video Paul.
I use this test for many actuators , windscreen washer pumps, fuel pump regulators, fuel pumps , and so on
Your career experience is solid information and I love practical remarks like that. In the AC world it is not uncommon for motors to die as a result of voltage drop in the supply line, although I don't know about DC automotive fuel pumps. It took me a while to understand why for example an AC well pump might die as a result of inadequate voltage from upstream or downstream electrical line resistance. When AC motors get inadequate voltage, they respond with the only thing they can do, demand more current to build enough power to overcome startup torque. That higher current for longer time leads to the tiny wires inside the windings getting hot and the motor burns up after that. To make things worse, the duty cycle of a motor getting inadequate voltage makes it work even harder for a longer time to meet demand. So, wise electricians may do a quick check of voltage at the new pump when it is working to reduce the chance of damage to the new pump. I hear you when you say that high current light bulbs aren't necessary for automotive diagnostics, but it is so easy to do that check, so why not?
i was just rewatched your video on test lights the other day long time subscriber i learn alot from all you guys thank you
I've studied this strange phenomenon. Not sure the difference with the AC and DC motors offhand, but this explanation makes sense: low voltage to a motor, equals less counter emf (counter voltage) the motor will produce because it is spinning slower. This is what limits current flow. The slower the motor spins, the higher the amperage. There are variables to this of course. But I've not seen a burned up brush type DC motor with the cause being a low power feed or good ground. I would say that if I had repeated motor failures on a circuit, I'd definitely be testing the power and ground with a little more scrutiny.
But I don't fault those who like to add additional loads. I just trust my meter and my test light results, so never had the need to go beyond these two tools.
Thank you for all you do for us, Paul!
I’ve made a few “noid lights” with various bulbs with wire leads and small T-pins to plug into circuits to load test, I usually use one that has a 9006 halogen bulb. In my earlier days, have been fooled a few times with a volt meter before I understood that a circuit needed to be loaded..
good you see you again bro , I've been testing voltage drops with a test light for years 😊
Awesome lesson and very helpful thank you!
Good lesson.
Excellent tutorial scanner
Seems simple. Thanks Paul.
Always great information and training. As always these are golden 👊🏻👍🏻
If the horn was good and the wires couldn't support the current flow you would see it with your meter or light as voltage drop. Thanks for all you do Paul.. 👍👍
Thanks for showing us this keep up the good work
Yes most awaited video of the week😍😍😍
Thanks for sharing SD👍🏻👍🏻👍🏻
Please share some latest case studies with James Danner😍😍😍
Always an honor, Stay Blessed Danner Family🙏🏻🙏🏻🙏🏻
Great video as always.
Great explanation.
Excellent work,teacher
I had a lesson in AC voltage on a heater. All my safeties tested good on resistance but no heat from 240 vac heater. Rigged up test live and tested each side of the safeties and on one I was getting 240 vac which told me the safety I was testing was bad because I was getting 120 volts from l1 and 120 volts on l2 that went through the heater to my safety. Now I get the phrase electricity follows the path of least resistance because if the safety was good then the heater would've gotten the 240 volts instead of the safety.
AC voltage troubleshooting is so weird to me at times lol. My electrical buddy says the same thing to me with the 12v DC systems
@@ScannerDanner for real especially when you get 34 volts on a neutral wire.
Awesome simplifying sir, thank you. 😊
Thank you so much Paul
You have isolated the component in question
This is where I would Continuity test across the horn input leads
No Continuity means - Blown Open Coil "No Need to Go any Farther"
(The Harder it has to work the more power it needs to do the work, It Becomes Exponential)
That much draw comes with that much heat
Heat and Current find the weakest Point & Pop, you're out of commission
But You're Teaching Voltage Drops...
In the vehicle it would be part of a system
There you would be best measuring Voltage draw in action
Good Show Thx Paul
Side Note
My New Fuel pump that's not pumping, did not prime using external pump, or vacuum pump
Tanks coming out!
After some rest and healing, I'm ready to do it Again lol
update
We're up n running
What did you find?
@@ScannerDanner
Pulled it, tested functionality in a cup of gas - Tested Okay
(Pump Works, that's not the problem)
The pump filter was flat on the bottom of the tank, I rotated it up, put it back in after readjusted the filter screen
Added Power to the contacts pump put 40 lbs onto the pressure gauge - Tested Okay
Vehicle Starts & Runs
Conclusion:
(I'd say the screen sitting against the tank bottom, eliminated it's ability to draw gas into itself ("Plugged it")
I'm Taking Er Off the Blocks
The Worst Job is Now Done!
"Next!" lol
thx Paul
Awesome! Info Paul aka Scanner Danner!
Shows how to diagnose properly then shows his Jeep on fire haha, just joking, I've been following you for a long time and you definitely know your stuff. I enjoy the videos and thanks for sharing your knowledge.
Man, that jeep....I'm still shaking my head. All that was done was a student did the valve cover gasket BUT, I blew chunks of heavy carbon out of the top of that engine to clear out the drain back holes (300k with crap oil change maintenance)
My theory. A chunk of that carbon landed on the exhaust manifold and didn't catch fire until I stopped to get coffee. It then lit and burned right below the main harness and fuel rail.
Thank you Mr. Danner! -from the Philippines
Always interesting content! Keep it up
As usual, great explanation Paul. Thanks bud. 👍👍
Horn quick test when connected like that is hit the back with a big spanner. Most likely it will make some sort of noise for a while, fixing the worn internal contact. Same for a failing fuel pump, a bit of percussive maintenance will get it to run possibly, till those brushes fully fail, or the commutator finally burns out.
That poor horse, The " pro's must have been out in full force. IMO I like the data that you instill in my noodle!
Thank you for both videos. It cleared some things up for me.
Glad it was helpful!
I also use Load Pro leads on a DVM, you can load the circuit with 500 ohms and confirm and resistance of the wiring is ok on both sides before the pump/horn etc.
I still love your videos Paul keep up the great content
Thanks man 👍🏻
Paul, Caleb great video!!!!
Both methods have their merits; a DMM provides a more qualitative measure, whereas the test light provides some load.
I wouldn't like to say which method is "Best" as always it pertains to the circuit in question. What's probability more important is knowing your circuit design and the limitations/variables of any tests you plan on making.
More importantly as Paul said, testing under load is vital and the consumer provides that "Load." I used to test with various load test lights before i properly understood Voltage drop, but hardly ever do so these days.
A more advanced progression of your diagnostic skills, is to understand the "Most likely" the root cause of failure, and not get caught up with obscure possibilities that almost never occur. I struggle/d with this for the longest time, and tend to always keep myself in check by asking myself the most likely root cause and parking anything else untill necessary.
Thanks for this comment. Couldn't agree more
Awesome Outstanding job thanks
Wonderful video thanks
You gotta put the blame on the mechanic for that Jeep going up in flames🤣
For sure!
Thanks to Paul for some great testing of indicator lights.
Now I'm looking through your playlists on RUclips, chapters 17,18,19.
The first videos in the playlist were filmed 10-11 years ago, you have a pilot lamp in the shape of a screwdriver, it would be interesting to know how long it worked for you, and are there pilot lamps on sale now in 🇺🇲?
I recently saw such a lamp on a Chinese 🇨🇳 website.
Oooh, this is the lamp that S⚡D had
Thank you very much for sharing tutorial videos on RUclips 👨🏼🔧....
We are working on an SD test light as we speak! I'll announce it when it's ready
Great video, I was wondering if you could make a similar video showing how to use your test light to power something on. I’ve seen you do it multiple times but still not 100% on how you know when it’s going to activate the component your testing.
Extraordinary detail !
Super helpful !!
I learned lots !!!
Thanks mate .
👊🏼 🔥 ⚡️ 🕊
Podrá acer videos en español.. gracias como quiera aprendo mucho bendiciones ❤
Great video, just wondering is it safe to use a test light on 5v sensor circuit to check for voltage drop?
Use a voltmeter. There is really no need to use a test light to test a 5v ref circuit. In some circumstances you can, but you need to know what you are doing and most certainly know the current draw of your test light
Nice👍
Like the channel - subbed from SE Texas Bear ❤💯🙏
Is it true that Texans love licking longhorn nuts.
A faulty component, (starter etc) can show (for example) 2.4 volts drop cranking could be a starter? If you know the cables ate good?
Amperage measurement would answer that 2.4v drop
I've been in a nightmare trying to help a friend on their 2008 gmc 1500 5.3. DTC showing no communication with TCM, no oil pressure reading at gauge, windows acting up. Testing at DLC, have 60 ohms on pins 6 and 14, Testing low speed bus splice pack under the dash, I'm averaging around 4.5v but every few seconds 11.2v is spiking for split second. It shows up as soon as the key is in accesory, plus run. It only happens on pin M once all other pins are isolated. Pin M goes to the BCM. Only way I've gotten it to go away is either pulling the DLIS 2 amp fuse, unplugging the ignition switch, or unplugging the X1 connector at the BCM. We've cleaned almost all grounds and checked most power connections. We've unplugged just about every module on low speed can bus, the spike stays on until the BCM goes to sleep. It almost seems like there's something going wrong inside the BCM circuit board. It spikes 11.2v every 3 to 5 seconds, then bk to 4.5v. Its been a nightmare lol.
What is the voltage range of the low speed bus you are testing? Is it a single or two wire bus?
You really need a labscope to look at network signals. Relying on an average voltmeter reading is difficult
I also feel like they both work as long as you understand the fundamentals of this test. But it’s more about people one guy is a numbers guy and one guy is just seeing if it works. I’m the numbers guy lol
" Wolves at the Gate " is an Christian metalcore band
Yes sir
Have you tried the load pro on a meter?
Never felt the need to own that tool. In part because the owner liked to bash me publicly lol.
Good tool, has its place, just not in my arsenal
I’ve seen a bad component and wiring issues “burned pins”
That's different. Burnt pins on a failed component is not wiring issues up further in a harness
So, maybe I missed it, but how does the meter show 12 volts at ground (17 minutes in) when the ground wire is open? Don't you need the positive side and the ground side to light it up? Ground to ground should not make it illuminate. Shouldn't that be a short? Where am I wrong?
He's trying to show what happens when checking an energized circuit with an open ground. The electricity flows through the resistor, then through one of the wires of the little motor into the little motor, but since the other wire from the little motor is not connected to ground, the motor doesn't run because the circuit is still open (not complete). You should read a book or watch some videos on basic electricity before watching videos similar to this. If you don't, it's going to confuse you and hinder your learning. Even better, grab a couple of light bulbs, some wires, a battery, and a voltmeter. Connect them in series and check them with test light and voltmeter. Then connect them in parallel and check with light and voltmeter. Check before and after every light and make note of the light and meter readings. This is basic. It's like adding 2 plus 2 in math and I'm not exagerating.
You are not wrong that a short to power on the ground side of a basic motor circuit could also cause the test light to illuminate. The next step would be to unplug the load (horn) and retest the ground circuit on the vehicle harness side. If the test light still illuminates, or meter still measures voltage on the ground circuit then this suggests a short to power condition on the ground circuit to the motor. A common cause for this that I have found is a bent pin in a harness connection. The ground circuit pin bent and touching a nearby power circuit pin. A less common condition than a failed horn or motor but still a valid question you presented.
@@wayneschirmeriii6487 A short to power on the ground side of one circuit is a short to ground on another circuit. This is not what Paul is showing at around 17 minutes of the video and that's what the question was. Paul is showing an open ground.
Since there is not a complete circuit. You will measure the voltage through the load. That’s why the meter reads 12V with an open ground. If the circuit was operating correctly. The meter would read close to zero which would indicate a good ground.
No current flow, equals no voltage drop. Power comes into the positive side of that motor and comes out the negative side "looking for a ground". A voltmeter will show 12v (same as the source) regardless of the resistance of the output. Let's compare 1 ohm (electric motor) to 150 ohms (relay coil) for this example.
Both circuits will show the same 12v with an open ground when using a voltmeter (no current flow, no voltage drop).
Now, let's use my test light. Remember that connecting this light, in this way, with an open ground, is basically putting another resistor in series after the load. The 1ohm circuit will have very little drop in voltage, so my test light will be very bright.
The 150ohm circuit will have a large drop in voltage and my light will be very dim.
There are variables within this test too, and one of them is my test light itself! The light I'm using draws about 200ma.
To put this another way. The motor I'm testing probably carries 3-4 amps and my test light can only carry 200ma, that is why the ground wire is so bright.
If this was a relay coil that draws less than 100ma, my test light would have no problem energizing that circuit (at least partially anyway) and the bulb would be very dim in that test as most of the voltage dropped across the first resistor. Lol. Now I'm rambling.
Lastly, you will never troubleshoot a short to power on a ground wire. Why? Because you would attack that problem as a short to ground on a blown fuse or possibly a blown out computer driver on a power side switched circuit. But even with that, you're testing the power feed wire for a short to ground. Never the other way around. At least in your head anyway.
What's up with all the female bots leaving comments? You know most of these women (probably men) aren't interested in videos like this. Even some of their comments don't make sense or relate to the video. I haven't seen this on other RUclips videos.
It's been every new video lately! I've been banning and reporting every one of them. They should be gone now smh.
Thanks for the heads up!
When the output is static, it's just a wire. For all those who would bust out the scope for this, you're wasting time. A scope is a good tool, but it is unnecessary for simple testing.
Can you wack that horn and make it work?
I believe I tried in part 1