Generator problem

[Deleted User]

When I turned the ignition key off my '51' Commodore the other day, I noticed the AMP light was still on. I jiggled the key, restarted the car, and when i turned it back off, everything was fine and the light was off.

I came out to take a drive two days later and the AMP light stays on when the car is running and when I checked the generator by grounding the field wire, the light stays on,and the battery voltage is at 6.1 with the car running and 6.2 or so with the car shut off. So it suggests the generator needs some work.

Something just doesn't feel right, I just have a feeling that it is not the generator. Why would the light stay on with the key shut off, could a bad ignition switch cause the generator not to charge even when grounding the field? The regulator is getting voltage from the battery, I checked that.



Maybe I'm making too much of the light staying on, but it had never happened before, and now the charging system isn't working. Any ideas?

mars55

Well, what could has happened is there was a short in the GA (gage) circult of the ignition switch. This welded the contacts in the ignition switch closed which caused your GEN light to stay on. Next the short fryed your generator. To prove disprove this you need to find out why your generator failed.

Geoff

The fact that the light stayed on when the ignition was switched off, indicates that there is still voltage being supplied to the bulb, which can only come from the ignition switch. the bulb is earthed through the generator armature, so when the generator starts charging these two voltages cancel each other out. Te check the generator, remove the fan belt, short "Field" to ground, and jumper between "Arm" and "Bat". the generator should turn slowly. If it doesn't, the generator needs attention. If it does, the regulator needs attention.

[Deleted User]

Thanks guy's,

I will check out the things you suggested.

[Deleted User]

In some cars regulator points can stick causing the light to stay on. As I recall, this can quickly ruin the regulator.