Alternator is grounding the power wire?
Thread Starter
Teching In
Joined: Oct 2009
Posts: 20
Likes: 0
Alternator is grounding the power wire? I'm using a '04 GTO style LS1 and loom in my retrofit. When I have the alternators battery wire connected (the thick red one) my entire loom's constant battery power is connected to ground.
When the alternator is disconnected everything is fine..
I did a beep test with a multimeter between the big battery terminal on the alternator to the chassis and there was connectivity.
I can't figure it out... Why is the constant 12+ terminal on my alternator connected to ground? I'm not sure if it makes a difference but, I haven’t hooked up my brown / white alternator wires to anything yet.
Any help would be appreciated. I’m stumped.
When the alternator is disconnected everything is fine..
I did a beep test with a multimeter between the big battery terminal on the alternator to the chassis and there was connectivity.
I can't figure it out... Why is the constant 12+ terminal on my alternator connected to ground? I'm not sure if it makes a difference but, I haven’t hooked up my brown / white alternator wires to anything yet.
Any help would be appreciated. I’m stumped.
Take it to a parts store that does free alternator checks.
There are diodes in the output of the alternator. Hook up the ohm meter one way and it is a short. Hook it up the other way and it is open.
Alternator windings have pretty low resistance when the alternator isn't spinning. Are you sure it is zero ohms or just a very low value?
There are diodes in the output of the alternator. Hook up the ohm meter one way and it is a short. Hook it up the other way and it is open.
Alternator windings have pretty low resistance when the alternator isn't spinning. Are you sure it is zero ohms or just a very low value?
Thread Starter
Teching In
Joined: Oct 2009
Posts: 20
Likes: 0
Thanks for the suggestions. I was thinking it could be a grounding problem too but I tested from the B+ pin on the alternator to the car chassis, I dont see how this pin could connect to the chassis other than through the alternator casing. I had all wires to the alternator disconnected.
I was leaning towards a bad diode. This engine came out of a working car so I'm not sure how this would have happened. Maybe I knocked the alternator when lifting the engine into the car?
Pop_N_Wood, is wasnt a 0 resistance beep. It read about 483 I think. I guess the next step is to pull the alternator apart and have a look. Are there any visual signs that I could look for that would cause it to ground like this? Burnt windings wouldn't cause this I guess?
I was leaning towards a bad diode. This engine came out of a working car so I'm not sure how this would have happened. Maybe I knocked the alternator when lifting the engine into the car?
Pop_N_Wood, is wasnt a 0 resistance beep. It read about 483 I think. I guess the next step is to pull the alternator apart and have a look. Are there any visual signs that I could look for that would cause it to ground like this? Burnt windings wouldn't cause this I guess?
Check a repair manual. 438 ohms might be OK. Windings are just a coil of wire. You can expect a low resistance.
A visual inspection can still miss problems. A good repair manual should tell you how to properly ohm out an alternator.
i would take it to a parts place that does free alternator checks first. If something is shorted out it will fail in their machine.
A visual inspection can still miss problems. A good repair manual should tell you how to properly ohm out an alternator.
i would take it to a parts place that does free alternator checks first. If something is shorted out it will fail in their machine.
Trending Topics
Thread Starter
Teching In
Joined: Oct 2009
Posts: 20
Likes: 0
Well, I pulled the alternator apart thinking that maybe something had fallen between the B+ terminal and the case shorting it. I couldn't find anything.
What I did discover was that when I measured the B+ terminal to the case with the multimeter probes the other way around it would not find any connection. I guess I was sending the probe voltage through the case and out of the B+ terminal, but it wont go back the other way due to the diodes.
I may have looked too far into this one :S. I'm just going to use it and see how I go.
What I did discover was that when I measured the B+ terminal to the case with the multimeter probes the other way around it would not find any connection. I guess I was sending the probe voltage through the case and out of the B+ terminal, but it wont go back the other way due to the diodes.
I may have looked too far into this one :S. I'm just going to use it and see how I go.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
