Power for the dash, heater control, clock & radio dimmable bulbs comes through the headlight switch to the INSTR fuse and then to the various bulbs that are all dimmed by twisting the headlight switch knob. If none of these bulbs light up it could be the fuse, connections or a broken resistor wire or other internal problem in the headlight switch. There are two dash illumination bulbs on each side of the speedo. These are fed by separate wires to the five-pin connectors on each side. Grounds for the bulbs are established on the PC boards via screws to the panel pot-metal chassis. I feel it is unlikely that both sides of the panel lights would fail due to bad ground or bad connections simultaneously. The courtesy lamps on the console and side panels should come on with the headlight switch knob turned to the far counterclockwise position. The courtesy lamps are not fed through the INSTR fuse which is the far left hand fuse in the fuse block and is a 2-Amp fuse.
If the problem is with the headlight switch, suggest disconnecting the battery. Removal requires removal of the knob and its shaft which must be released by pressing a small, spring-loaded button on the bottom of the switch which releases the shaft and allows it to be pulled out. Always more difficult than it sounds—but that’s the only way. Then the round bezel must be unscrewed to release the switch. Make yourself a special tool to engage the two small holes on the bezel or use a tiny-tipped needle nose pliers. The switch is fairly universal and readily obtained. You can test the removed switch by checking for continuity between B1 and INST terminals after pulling out the shaft to the park light or headlight position and twisting the re-inserted shaft.
Have fun under the dash while learning more about the under-dash wiring. Best wishes for the problem being just a fuse.
Would like club input on why my dash lights do not work, could it be the rheostat switch is worn out, if so where do you get one and how hard is it to replace?
Posted by: "Rich Barber" <c300@xxxxxxx>
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