View Full Version : Gen light on when ignition is off

05-24-10, 04:32 PM
Hey guys, I have a recent engine and starter replacement on my 69 Deville...
I now have an issue and I am hoping someone can point me in the right dirrection.

My Gen light is on when the ignition switch is turned off...
The Gen light goes away when the key is turned forward....
The alternator is not charging the battery.

any ideas?

05-24-10, 05:21 PM
I have the same problem with my 69, but it also makes a buzzing sound. I'm assuming it's something worn out in the ignition switch it's self. If I jiggle mine, it goes away.

05-24-10, 09:24 PM
One cause of the light being on with the key off is a shorted diode. Also, this will cause the buzzing sound and sometimes create a vibration you can feel in the steering wheel. Back that far the alternator is servicable. Long time ago a diode bridge what not expensive.

05-25-10, 12:34 AM
Have to agree, bad diode. I do know the GEN light will light dimly when the key is in the ACC position.

05-25-10, 07:32 AM
Thanks for the thoughts...I'll look at the alternator diode.

05-25-10, 06:58 PM
If the light is on brightly, car off, the alternator is shorted internally. If its on dimly with the engine running, its usually a failed diode trio. Both point to repair inside the alternator or alternator replacement.