My 89 XJS's gauge cluster will not illuminate when lights are switched on. The computer illuminates but nothing else. Not the gear shifter, not the gauges, not the cig. lighter. I checked for blown fuses and didn't find any and I do have power to the fuse that runs gauge lights and reverse lights. I don't know if its related but this only started after I rinsed down the engine compartment. I don't yet have electrical diagrams which REALLY isn't helping. Any suggestions?

 

Remove the dash liner, driver's side, make sure you have power going to the dash light rheostat (dimmer) from the parking lamp switch. The rheostats fail, if there is no power out to the instrument lights then thedimmer is bad. Assuming it is not turned off, that is.

You can justgang all the wires together and leave it that way if you want, normally operating instrument illumination is not very bright when it's cranked all the way up, anyway.