Electronic Q on a 4.3 GM

[Chad Sheets]

Nice friend of mine came over with his mid 90's 4. 3 Blazer. The battery was getting drained overnight.

I unhooked the ground and put a multi meter in between the ground on the battery and the ground cable. It was showing a 12. 6 volt draw. I went to the altenator, unhooked it and the draw went away. This means the altenator is bad, correct.

While running the battery was in the 13. 5-14. 5 volt range, and the altenator was putting out 14. 5 volts. If you let it run long enough, it would just give up and die.

Do you think I told him right about the alt being bad?



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Always ready to help!
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[illflem]

Chad,one bad diode will do what you describe,I think you were right on.

 

[Chad Sheets]

Man do I hate electronics! He got a new alt, and said the battery isn't draining anymore. I was a little shocked when he told me he took it to a dealer and they told him to replace the battery, coil, cap/rotor and plugs and wires. He has no clue on mechanical stuff to speak of, didnt know any better. After he did all that he asked me to look at it. Just reinforces what we are always complaining about with the dealer tech not having a clue... or maybe they do have a clue, but want you to get upset, give up and bring it to them to fix for $55/hour plus parts. Gotta love dealerships.

 

[illflem]

For future reference-most good auto parts stores will check the alternator if you bring it in to them. Then it's an easy matter to leave it there for the core charge on a rebuild if it's bad.