[Elliott]

Ok, I have a 1975 AMC Gremlin, all original, 232 straight 6, not even 40,000 miles on it. A few nights ago, I was driving home from a friend's house, alternator died (showing 12.6 volts at the battery when running), made it home, charged the battery and changed the alternator the next morning.

First replacement alternator charged the battery fine at 14.7 volts, but the ALT light was staying on when running, but was off when the car wasn't running but had the switch on, which is also not right. I took it back and had it tested, and the diode pack was bad out of the box, no big deal, it happens. Got the replacement.

Second replacement also charges the battery fine at 14.7 volts, but the ALT light is still acting the same. It tested fine though at the store and is definitely not the problem.

A few more very important clues:
I noticed my gauges are reading low and the BRAKE light in the cluster, which is supposed to come on along with the ALT light when the switch on and engine off, isn't coming on either. If I start and stop the engine a couple times, I can occasionally catch a little flicker of the BRAKE light just as the engine starts.

This is a simple Delco 10SI 3 wire internally regulated alternator, one big wire goes to the battery for charging, one goes to the idiot light and one goes to the ignition switch for voltage sensing.

I have already solved this, and I feel extremely stupid now, lets see who can guess the problem.