1990 GMC C2500 • V8 2WD Automatic •

GMC 1990 back up light do not turn on and on left back side signal light do not work.
Sylvia Medina
January 4, 2011.

I have replace Tail Lamp Circuit Boards and Lights.

Sylvia Medina
Jan 4, 2011.
If there is no power to the circuit board, you need to trace the wiring to see where it is lost. As far as the back up lights, check the switch on the transmission. As far as the signal lights, check wiring. NOT a fun jub, but you need to trace down the wiring until you find where there is power. At that point, check the wire itself for damage. NOTE: Check plugs and even if the wire looks good, always check for continunity. It could be an internal break.