[Ryankey]

I think I am having an alternator problem in my 69 chevelle. The red "Generator" light on the dash stays on even when the key is out, and all the electric circuits SHOULD be off. Why is this?

My battery seems to be always going dead too. Anyway it just started doing this within the last week. I heard a way to test the alternator is to get the car started, and remove the POSITIVE battery cable from the battery while the motor is running. The car should continue to operate properly if the alternator is in good working order, however my engine died right away.... SOoo is my alternator bad or what??

 

[Wes Briscoe]

Pulling the positive cable off is not a way to test if the alternator is putting out. Old school guys will say this is the way, but is isn't. Doing it will generally lead to you blowing out a diode in the alternator, and then it WILL be bad.

Best way to figure this out, start the car, put a voltmeter up to the battery if your reading battery voltage or less (12.6 or below) your not charging. If your reading 13.0-14.8 (optimal) then your charging.

If your not getting a charge to the batter, put the positive lead of your voltmeter to the main pos lug on the back of the alternator, and ground the negative side. If your getting the same amount of voltage as at the battery, then your alt is bad. If its higher (13-45V) then your regulator is bad.

If you don't have a voltmeter, most battery shops will do this test for free and it takes less than a minute.

If none of your wiring has been changed, its entirly possible that your alternator has gone bad and is backfeeding the system which in turn is killing your battery (not to mention it not being recharged). I've never seen one ground the light on all the time..but anything is possible.

Hope this helps.
Wes

 

[JWagner]

Try unplugging the regulator connection and see if the light goes out. It may be that the relay for the light is stuck in the closed position.