Having instrument light issues. 1990 RRC. I've got none. No cluster. No console lights. As far as I can tell no lighting power to the cluster. I've got turn signal indicators, high beam, oil/temp light. Fuel gauge and temp gauge. I've got dome lights, horn, head lights and tail lights. Zero interior lights. I've got a broken wire on the rheostat but temp fixed it back together. There was a mystery wire tapped into on of the 3 wires. It abruptly ended. So I don't know what it was feeding. I've removed it. I've tried jumping the wires on the rheostat. No luck. I've traced all fuses. I've checked/cleaned the three main grounds I know of. 1. Under air filter. 2. Under coolant bottle. Under steering column. I pulled the cluster cleaned/checked bulbs and the flexible circuit board continuity. I've got a couple of bulbs out but some should be lighting. Verified ground continuity. I'm assuming there's a relay responsible for these lights? I'm kinda stuck at this point and would appreciate a nudge

 

So I figured I'd post an update since all the old threads I read abruptly ended w zero explanation.

My issue was... someone tapped into my instrument light's dimmer function. I assume maybe for a radio or part of the giant 90s car phone that was installed in this truck.

I bypassed the dimmer early on but still no lights. I didn't realize the Classic only has 4 lighting bulbs for the cluster. Two of mine were out and two sockets were completely corroded not allowing contact. Hence no lights. You can see the crusty green in the pics. Replaced bulbs w LEDs and cleaned up the entire board in back. Now all the lights work. No dimmer at the moment but I always have gauges at full bright anyway. Hope this helps some one w the same issue.