Weird cluster problem

[USSkoval]

The gauge cluster in my '77 just started screwing up a bit. When you turn on the headlights, everything is fine for 15-20 seconds, then the back lighting for the speedo and gas gauge go out, the gas gauge quits working, the right turn indicator lights up constant and the bright indicator lights up a little. The turn indicator will still flash when the turn signal is used. It only does it with the headlights on, and it does not affect the four smaller gauges at all.

Would this be a bad cluster or printed circuit? Or do I need to look somewhere else for a problem?

[ron350]

The instrument cluster on my 75 did something similar and the ground trace on the printed circuit had cracked in more than one place.
On my 75 there is only one ground wire supplying ground to every thing on that cluster and it snakes all around on the plastic circuit.

You could also have a bad connection where the wiring harness plugs into the cluster.

[nlped]

Curious. My '87 the left blinker stays illuminated when the lights are on. It still blinks when activated and doesn't illuminate when the lights are off. I guess I will have to have a looksy at the circuitry...

[Prong]

If it only acts wonky when the headlights are turned on, it might also be the headlight switch.