1968 Firebird Printed Circuit Bulb
 

Replacing the printed circuit on my 68 Firebird convertible...….generator light is very dimly lit while running and I was told that the printed circuit is probably the problem. Anyway, I took the dash/circuit out and the bulb holder (see attached) in the upper left position of the attached picture is not like the others. Best I can tell, it should have a hot wire running to it.....I would guess from the lighting circuit so it can be on, off, dimmed; however, the nearby wire that is not attached is hot at all times when the key is on. This wire is yellow. I have not been able to determine what the wire goes to. Anyone know if it is the wire that goes to the "different" bulb holder or where it is supposed to go? Am I correct that the "different" bulb holder should have a hot wire and be controlled by the lighting circuit?

The hot in run yellow wire does not go to dash lights. Power and ground for them are in the plug-in/connector.

Pull the radio fuse and see if it cuts power off to the yellow wire.

I suspect the trick bulb socket is a jump off point for some other dash lighting. Maybe for heater controls, radio, ash tray.....Just something along that line.

Gen light glowing is usually something going on with the charge circuit. Like voltage regulator or something keeping the alternator from charging like it should.

Clay

Thank you; makes sense! Sense is something I do not have when it comes to car wiring.

Randy

that is for the fiber optic ash tray light ,,,
or lighted 68 ignition switch,,,,
you may find a black stiff wire looking fiber optic cable running to your ash tray support bracket at the top
or to the ignition switch next to the dash,,,
I agree yellow is power to the radio

Scott

Fiber-Optics
 

There's one version they had; it lights up the slot in the dash mounted ('68 only) ignition switch. That one is pretty rare. The most common one you'll find is the one that lights up the ash tray. GM used these fiber-optic cables in and around the dash cluster from 1968 up well into the mid-to late 1970s on many of their cars.

Thanks everyone!