Also have a question on my interior dome lights.
When i open the front doors, the dont go on. They also dont go on when I turn the dimmer dial all the way to the left to turn them on.
But they go on when I open the back doors. Could this be a switch or a fuse?

Kas

 

I would check the fuses first.

 

Dome lights use the ground for switching on and off. Usually, all the doors and the dimmer switch is all one circuit. Now if the rear door will make the light come on and no other swiches will, I would suspect a break in the wire between them. I don't have a diagram for a 92 but i'd bet the wire is corroded at the splice where the front door jam switches meet the wire from the dimmer switch, or the wire is broken between the front switches and the rear switches with the light being after the rear switches in the circuit.

 

That is not entirely true. Each switch can independently complete the ground circuit for the interior lighting to turn on the lights. Each switch is run in parallel with the rest.

If a fuse is not blown, I would suspect something is amiss with the dimmer switch. I'll take a look at the wiring diagram if I can find it to help clarify things.

 

Sorry, I guess I wasn't clear. Each switch, being either a door jam switch or the dimmer switch will ground the same wire going to the light. Most are just one circuit, but mutiple circuits are possible as like my rear cargo light.

I went though this with my Bravada. The dimmer and none of the door swiches would not turn on the rear cargo light and the rear door switches and hatch would not light the front dome lights. When the hatch was opened, only the cargo light would come on. I pulled the left front and rear seats to lift the carpet to get to the wiring harness. The wire connecting the dimmer switch to the front door switches under the dash was OK as the dome lights up front worked. So I traced the harness to the rear door switches. The splice where the door switches connected to the wire for the rear cargo light was completely corroded apart. When the hatch was opened, the ground going to the front lights stopped at that splice as with the ground from the dimmer switch to the cargo light. The rear doors switches ground was stopped there also. Repairing that splice fixed most of the interior light problems.

The hatch has it's own circuit for the cargo light(2 sets of terminal at the light) and that's why it worked with the hatch.