Bad Alternator?

[klaatu42]

Hi.

When I turn the key on #3133, the battery light does not come on. I pulled the connector from the alternator and connected the Brown/Yellow wire to ground and now the battery light does come on when the key is turned.

Does this mean the alternator is definitely bad or could this still be coming from somewhere else?

Incidentally, #3133 starts, runs until the RPMs ramp up, then it dies (1 - 3 seconds).

[DMC5180]

Please provide a little more background detail. Did this just happen or is this a project resurrection car. Do you know the history of the alternator? What brand? Was it replaced with a newer version or is this a Motorola (single wire) or ducellier ( two wire)?

[David T]

Hi.

When I turn the key on #3133, the battery light does not come on. I pulled the connector from the alternator and connected the Brown/Yellow wire to ground and now the battery light does come on when the key is turned.

Does this mean the alternator is definitely bad or could this still be coming from somewhere else?

Incidentally, #3133 starts, runs until the RPMs ramp up, then it dies (1 - 3 seconds).

The alternator could be OK but the voltage regulator went bad (it's inside the alternator). Is there sticky black goo dripping from the bottom of the alternator? Take the alternator off and have it tested. If it is a Ducey just replace it. Other wise it could be tested and rebuilt. Your test DID prove out the car's wiring and the trouble is the alternator.

[DMC5180]

The alternator could be OK but the voltage regulator went bad (it's inside the alternator). Is there sticky black goo dripping from the bottom of the alternator? Take the alternator off and have it tested. If it is a Ducey just replace it. Other wise it could be tested and rebuilt. Your test DID prove out the car's wiring and the trouble is the alternator.

Or it could be a poor case ground which can be verified by grounding the brown/yellow to the alternator case. It sounds like this is a resurrection car that has been sitting for years, based on info in another thread.


Dennis

[DMCMW Dave]

If the light goes on when grounded but not with the usual key-on/engine off test, the regulator has failed.

[klaatu42]

Or it could be a poor case ground which can be verified by grounding the brown/yellow to the alternator case. It sounds like this is a resurrection car that has been sitting for years, based on info in another thread.


Dennis

Thanks, Dennis. I was actually going to try this out on a hunch, but wasn't sure if this was a safe thing to do. I may go try this now before I lose the light.

Yes, indeed, I traded a '70 Maverick for #3133 and have been working to untangle the mysterious history of this car ever since. Previous owners have made this journey a difficult one. Lots of little mistakes and botched installs. Normally I like to focus on one issue at a time on a vehicle so as not to confuse things, but I have no choice with this one. Very glad to have #11633 to drive while I get it sorted! Even more glad to have so many helpful people here on the forums!

I just pulled the bulkhead connectors for the first time (not sure why I hadn't done this yet) and found that they are VERY corroded... as in GREEN. Thinking some of my other electrical issues might be coming from there. Thorough cleaning soon. From what I've seen so far, every connection that can corrode has corroded. Fun fun fun!

[DMC5180]

Well then, regardless of your grounding to the case test, you should remove the alternator and mounting lug from the engine and give all mating surfaces a thorough cleaning since your dealing with a corrosion problem. You may be chasing grounds too.


Dennis