Learn how to diagnose electrical

GBJeffOH

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Nov 17, 2014
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How to (voltage drop) test a starter motor circuit

 
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Dustyx2

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Feb 19, 2021
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Most valuable testing you can do when you have a no start condition. Finds bad connections, a bad battery,
bad cables, switches, you name it. Practically no one knows of it. Too often it's just start by replacing things until it works or they give up.
 
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AndyM

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Most valuable testing you can do when you have a no start condition. Finds bad connections, a bad battery,
bad cables, switches, you name it. Practically no one knows of it. Too often it's just start by replacing things until it works or they give up.
Well this is timely - went to start the Polaris ATV yesterday (about 40 hrs on it) and nothing. Dash lights then, fuel pump kicks in, then nothing. Ordered some manuals, then away we go I guess.
Hope I don't end this giving up!
 

Trash Panda

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L2501
Feb 18, 2022
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Most valuable testing you can do when you have a no start condition. Finds bad connections, a bad battery,
bad cables, switches, you name it. Practically no one knows of it. Too often it's just start by replacing things until it works or they give up.
Come on.

One of my favorite activities is blasting the parts cannon at a phantom electrical issue! It buys me hours of uncontested shop time. If I’m not having fun on the surface level, I’m left alone to blast Alice In Chains and crush Miller High Life!
 
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Dustyx2

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BX22, M7060, Landpride RC-2512, Woodmax SB84
Feb 19, 2021
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Well this is timely - went to start the Polaris ATV yesterday (about 40 hrs on it) and nothing. Dash lights then, fuel pump kicks in, then nothing. Ordered some manuals, then away we go I guess.
Hope I don't end this giving up!
Just remember you have to test under load for a voltage drop test. Eric O. at South Main Auto youtube just had a voltage drop test video on an alternator that was interesting. Real world example.
 
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Mark_BX25D

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Just remember you have to test under load for a voltage drop test.

Yep. No load vs. loaded are two different worlds. This confuses a lot of people.

Loaded vs. no load is why I like to use BOTH a test light AND a multimeter.


Eric O. at South Main Auto youtube just had a voltage drop test video on an alternator that was interesting. Real world example.
That's an excellent video.
 
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GeoHorn

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How to (voltage drop) test a starter motor circuit

THIS particular video FAILS to show the “fault” which was introduced. It makes the basic point…but Does Not convince because it Never demonstrates the failure….leaving the viewer (yourself) still bewildered as to WHAT IS THE PROBLEM.
(minor point: He also mis-uses his own terminology when discussing the solenoid terminals. He identifies the “M” terminal …then later Mis-identifies it calling it incorrectly.)
This video should be edited by the producer.

THUMBS DOWN.
 

AndyM

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Just remember you have to test under load for a voltage drop test. Eric O. at South Main Auto youtube just had a voltage drop test video on an alternator that was interesting. Real world example.
I only did a quick check but a no load test came back at 13.3v; with the circuit on it dropped to 12.6v. More to do, but I would conclude the battery is not the issue.
 
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jaxs

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It was recently suggested on another tractor forum that a teaching thread be posted on this very subject. Resistance to the idea made it clear members like going back and forth arguing who's method is best when someone asks for battery/starter help. I shudder when I think of how much expense and frustration I'd have were it not for my multi-meter.
 
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ruger1980

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L4310 w/La682, L225
Oct 25, 2020
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It was recently suggested on another tractor forum that a teaching thread be posted on this very subject. Resistance to the idea made it clear members like going back and forth arguing who's method is best when someone asks for battery/starter help. I shudder when I think of how much expense and frustration I'd have were it not for my multi-meter.
Everyone here would sh*t themselves if they had seen some of the bills I have seen and had to deal with regarding technicians and management either loading the parts cannon or running down the wrong path with blinders on. Some of them are well over $200k. The last one, earlier this week was probably only $20k. They called me Wed. and said we got it fixed and said it was something stupid they overlooked and I had told them exactly how to trace the power in the circuit.
 
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jaxs

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B1750HST
Jun 22, 2023
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Even among auto and equipment techs, people who actually understand electricity are pretty rare.
Troubleshooting electrical is sort of like "give a man a fish and he will eat for a day, teach a man to fish and,,,,,,,,,,,,,,,,,,,."