Hi guys...this last Sunday I noticed my voltmeter gauge on my 85 GT started dipping to around 12 volts but the car drove ok. A little later the car started getting hard to start and then I noticed the gauge had dipped way down to 8-9 volts. Long story short, I got a jump from a stranger but the car simply didn't make it home. (it was obviously running off the battery only) Anyways, I charged the battery and got the car home. As a test, I turned the key to the On position and I noticed the center aux gauge voltmeter red light did come on. So, if the alternator is not working period, how come the light didn't come on?
P.S. As an FYI my 85 GT has the 86-88 GT center guage pkg. (I upgraded)
Maybe I wired something wrong?
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 04-26-2016).]

Maybe it's something as simple as a burned out bulb?

If the bulb is burned out, the alternator won't charge. It will eventually drain the battery.

I think he said it did come on. Isn't it the other one, the one on the dash, that you need for charging? It provides the resistance needed to "excite" the alternator and make it charge. In other words you may simply need the dash alternator light bulb. It should also come on with the ignition on, engine off.

On the pre-88's the alternator regulator plug is on the bottom. Maybe it fell out or became loose.

The 85GT used the battery light in with the speedo and tach. Later years moved the volt light in with the auxiliary pod over the heater vents.

The alternator in my '87 SE went bad once... the battery warning light didn't come on until the battery was almost dead (engine started sputtering). That's not much of a warning.