Alternator (GEN) light on when key is off.

[Hugger Orange 69]

I just had to replace the battery in my 69 Camaro.  When I reconnected the cables I noticed that the alternator light was on even before putting the key into the ignition.  When I start the engine the light goes off, but when I turn the car off the light comes back on and stays on.  I have to remove the cables to protect the battery from draining.  I am not very good with electrical problems.  When I remove the connector with two wires from the alternator and connect the battery the light does not come on.  I also notice a click from the voltage regulator every time I connect and disconnect the battery cables.  Could the alternator be bad?  What about the voltage regulator?

Some additional background: I have had a battery discharge problem since I purchased the car 5 years ago.  I think I have isolated that problem to the door switch.  Since I had the typical starter solenoid/heat problem, I switched to a mini-mag starter about a year ago.  This solved the heat problem, but not the battery discharge problem, so I recently returned to the stock starter and added a heat blanket.  When I installed a new battery last week, the alternator light issue popped up.  I have a Pertronix ignition system and a Code Alarm system that is tied into the previously mentioned faulty door switch. The alarm also operates the door locks.

Any help would be greatly appreciated.


Jim

[bertfam]

Jim,

If you accidently put the battery cables on the wrong terminals when you hooked up the battery, you probably popped the diode(s)s in the alternator. (Ask me how I know this!!) Don't feel bad, it happens all the time...

The only "fix" is to either find and replace the bad doide(s), or get another alternator. If yours is "numbers matching", replace the diodes(s). it's farily easy to do, but you do have to take the case apart. If you're not concerned about numbers matching (which it sounds like from your post), get a new alternator from your local jobber.

Ed

[Gramps69Z]

Most cities have a starter-alternator repair shop that will rebuilt your unit.  Look in the phone book for one. If not look on the net for a rebuilder. Like Ed stated, the diodes are bad, and aren't that hard to replace.

Fireman John   

[bertfam]

Jim,

You don't necessarily need a new Delco unit. A rebuilt one from Auto Zone, Pep Boys, Kragen, NAPA, etc... will work just as well.

As for what caused the problem in the first place, that's difficult to say. If you KNOW that you didn't accidently reverse the positive and negative cables (even for just a second since that's all it takes), then you have to start looking elsewhere. Although not very common in the way of popping diodes, it "could" be the regulator. But really, that's about it.

Did you have the 3 shops check the diodes?

Ed

[rich69rs]

You can also do it by jump starting a car.  Made that mistake backa about 10 years ago when I tried to jump start my '66 Chevelle with my '69 Camaro.  The battery in the Chevelle was drained way down and the little 37 amp alternator on the '69 didn't like the strain.  Damaged diodes were the result.

As Ed said, repair was no big deal, took it to the local starter/alternator shop and $35 later all was well again.

[JohnZ]

A key thing to remember is that alternators are NOT designed to charge a dead battery - their job is to maintain the correct state of charge. If you're dealing with a dead battery, you're better off to bring it up with a charger first.

[rich69rs]

John makes a very valid point - which was exactly the problem when I tried to jump start my Chevelle with the Camaro.  The Chevelle battery was basically dead and I tried to take a short cut.  Lesson learned.

[bertfam]

Jim,

Sorry to hear about your "adventures". Take the alternator back to them and tell them your discovery. It may be something as simple as them having to change the front case for some reason. I always recommend talking to them before jumping to conclusions. I'm not familiar with that particular shop (I live in Murrieta, so I know most everyone in the area), but I sincerely doubt that a reputable rebuilder would do a "bait and switch" on you.

If you can't get satisfaction from the guy behind the counter, ask to talk to the manager or owner as the case may be. Make sure you stay level headed and don't get into a pi55ing match!! Check to see if they're a member of the BBB. If so, and you can't get results, contact the BBB and lodge a complaint. If it's happened before, they'll know about it and investigate. If it's an isolated case, then there's not much you can do except vent here!

Keep us informed...

Ed