What Is A Voltage Drop Test?
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- čas přidán 23. 07. 2024
- A voltage drop test is possibly one of the most under-rated tests to be done when diagnosing a fault. It is a simple test and yet yields definitive results that can make your diagnostic time and effort minimised.
#voltagedrop#diagnosis#automotivemaintenance
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MiracleMAX wants you to be safe, however, no guarantee can be given against improper use or unauthorised modifications on the information provided. The repair shown in this video is carried out at your own risk and any property damage or injury is your own responsibility. Please ensure you carry out this repair safely using approved safe work practices, correct use of recommended tools and equipment. This video is educational only and is no guarantee of a result if done incorrectly. Any injury, damage or loss due to incorrect use of tools, information or equipment is the sole responsibility of the person carrying out the repair and not MiracleMAX.
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Thank you Max
You are welcome. You might like to subscribe to find other helpful videos 😁
Thanks again max I will be using this to check out for voltage drop for my vz sv8.
Let us know how you go! 😉
G`day Max ,
Problem solved ,Pajero 2002 DID (Zexel VE Pump 3.2 ) had a No start with Crank , tests , Stop solinoid , fuel tank pick up, power to all sensors 12vdc and 5 VDC rail , Glow plugs , all relays load tested and signals from sensors on ocilioscope (Nice square wave pattern , after a quick chat i did a voltage load test on the negatve wires from the speed sensors on the pump (there are 2 speed sensors Like a crank angle sensor 3 wire ) the NEGATIVE had a 2.4vdc drop to the negative on the battery , Bingo i jury riged a wire to the sensor common and hit the key and all good ,
Thanks again for the advice
Robert
Nowra
NSW
It was great to be involved with the diagnosis. Its an awesome feeling when you discover a possible fault, fix it and then hit the key to hear the beast roar back to life. Glad it's up and running for you.
Thanks for contacting me with this puzzle! 😉😁👍
Thanks a lot 👍
You are welcome! 😊
Well done mate 👍👌
Thank you! Cheers! 😉👍
Very informative video
Glad you liked it
Cool max, i didn't know a multimeter could be used like that.. i just learnt something that I'll be using a lot from now on
Glad you got something from the video. You might enjoy the multimeter playlist on the channel czcams.com/video/ldM2FdjfPRE/video.html
Voltage drop is often overlooked in diagnosing electrical issues. I remember working on mk3 Cortina’s that had a VD of 3 volts in the headlight circuit due to under size earth wiring and was upgraded as per service bulletin.
Fluke has an excellent pdf on VD testing for vehicles on their web site that may help some confused people.
Modern vehicles are intolerant of voltage drop and can lead to all sorts of issues.
You are right Colin. We are finding more and more issues with voltage sensitive circuits. Voltage drop testing is the only test for definitive results.
Thanks for your comment 😉👍
Very methodical explanation Max . Just need 1 thing clarified plz : since the 2.6 v voltage drop ended up being on the positive side of the load , wouldn’t that mean that this drop happened somewhere in the cable that’s between battery + & alternator output - in turn, indicating that this cable must be replaced since it’s the culprit of the drop?
Yes, that is correct. That's why I explained the fault I had put in to show the students what voltage drop is.
czcams.com/video/gX5djxG24oI/video.html
Thanks for your comment 👍👍
Thank you. More explanation/details for each test would be helpful.
Hey James, what are you referring to?
@@MiracleMAX
"Low charging situation"
What exactly is a low charging situation?
You showed us the voltage loss on the calculator, but could have reiterated that all the voltage output of the alternator is not getting to the battery.
Explain exactly why there should be no voltage between the alternator output and the negative battery terminal.
Explain what the "positive side of the charging system" is. What is wired to it? Where do the major wires go?
Why is "loading up the system" a more thorough test?
Terminal to post test: what exactly does that prove?
Alt output to alt cable test: explain that the 117 millivolts are lost just in that one connection.
"Bypass the positive lead." Tell us exactly what cable you bypassed. It runs from where to where? Why did your jumper cable produce the correct voltage?
I have no idea why you inserted the 1 ohm resistor.
Perhaps this video is made for professionals, but I fix my own car. I answered most of my questions by watching the video again, but many things were fuzzy. Very helpful, but much better with more details and explanations.
@@jamese9283 Hey James, I'm sorry that my explanation seemed difficult to explain. Let me try and break it down further for you.
What exactly is a low charging situation?
The charging system is not satisfactorily charging the battery and supplying the electrical needs of the vehicle.
You showed us the voltage loss on the calculator, but could have reiterated that all the voltage output of the alternator is not getting to the battery.
czcams.com/video/gX5djxG24oI/video.html I stated that what was being supplied to the battery was not acceptable, but what was being created at the alternator was within specification. Therefore we needed to find out why there was a discrepancy.
Explain what the "positive side of the charging system" is. What is wired to it? Where do the major wires go?
czcams.com/video/gX5djxG24oI/video.html I state that the output wire of the alternator back to the battery positive is the positive side of the circuit that I am testing
Why is "loading up the system" a more thorough test?
Loading up the system will stress out things more and accentuate any voltage drops
Terminal to post test: what exactly does that prove?
This proves whether there is any voltage drop between the terminal and the post - a loss of voltage which may be created by corrosion on the terminal.
Alt output to alt cable test: explain that the 117 millivolts are lost just in that one connection.
czcams.com/video/gX5djxG24oI/video.html I state that this test is done to test for a poor connection, resistance or corrosion. I am looking for a voltage drop that will be stolen from our load, in this case, the battery.
"Bypass the positive lead." Tell us exactly what cable you bypassed. It runs from where to where? Why did your jumper cable produce the correct voltage?
czcams.com/video/gX5djxG24oI/video.html I state that we know through our testing that the fault is in the positive lead, so we can bypass the faulty wire with another cable that we know is in good condition. As mentioned, this is done from the output wire of the alternator to the battery positive. We have therefore bypassed the faulty wire with a good one and restored the full alternator output back to the battery.
I have no idea why you inserted the 1 ohm resistor.
I am a teacher at a college that teaches automotive apprentices, so this is a simulated fault that you may find in the real world in the form of corrosion. This helps the students better understand the concept of voltage drop and the testing techniques.
I hope this clears up any areas that you may have had trouble with.
You may find other videos on the channel that help explain systems that will help you when working on your own car.
Thanks for your comment
MiracleMAX
@@MiracleMAX Thanks for the additional input. You helped me diagnose my car issues.
@@jamese9283 That's great news!
Hi are you in australia? I am so frustrated trying to find somebody to do this test for me! I'm in nsw.
What test did you have in mind? You can contact me at miraclemax3@hotmail.com
@@MiracleMAX thankyou. I need a dropped voltage test done on the earth circuit in my car to find what is causing the resistance and messing with the computer -throwing false codes and so on. I took it to an auto electrician who charged me $315 and all they did was a basic code scan in my car!!! I had told them I've already had multiple code scans run and not to trust the codes because that was the whole point I was bringing it to them. I had specifically asked for a drop voltage test. They didn't do it. I even have my own obd scanner. I'd told them this. Daylight robbery and not a damn thing diagnosed or fixed. There are a bunch of electrical gremlins-and i gave them a list but they were just out to rob me. I've called other places and I think because I'm a female requesting this test, they treat me with utmost disrespect and tell me they'll do anything BUT a dropped voltage test. It's infuriating!
@@rjansen4475 Sounds like you certainly have had the run around. Might be best to email me to further the conversation & confirm more details. You could also provide me with the list of what the auto elect provided you.
I haven't got an Email from you as yet. Have you entered the correct address?
@@MiracleMAX oh apologies, i hadn't sent it yet. I will send one now.
FYI, it isn't when you drop your millimeter.
Naturally, you would have to have it in the voltage range, otherwise it wouldn't work 😉😁
@@MiracleMAX You'll get no resistance from me.
@@MrWilliam.Stewart So is that the current topic of conversation?
@@MiracleMAX Well at my age, the topic is normally around impedance, but it depends on the frequency.
@@MrWilliam.Stewart We could go on forever, perhaps with regular continuity😉