When I was trying to diagnose why my 90 XJ40 wouldn't start, one of the things I did was to check out all the relays under the dash. I switched each one out, one by one, with a known good one. I finally figured out the problem was water in the gas tank. But now that I have everything put back together and running, my lights have gone wacko on me. The main dome light stays on, the instrument panel lights do not work, and the tail lights on both sides do not work, but the reverse lights do. The left hand rear turn signal does work. The right hand turn signal and brake lights have had issues before, but the tail light on that side always worked. I have checked all the fuses and they seem fine although the lightning bolt icon is lit up on the dash. I am willing to concede that it could just be a matter of blown bulbs on the right rear, but what about the instrument panel lights? All the lights that come on when you first start the car are lighting up. But the speedometer, odometer, oil pressure, fuel gauge, amperage (battery), and temp gauge do not light up. I have also checked the dimmer control and it does not affect anything at this time although it used to work.

When I was checking out the relays a couple of them did not want to come out, so I slipped a table knife in to pry them just a little (dumb, I know). I heard a little bit of a zap a couple times. Could I have fried something? If so, what?

Thanks in advance.

 

Check all of your grounds,make sure they are corrosion free (the ones in the trunk are usually in bad shape). also the fuse boxes sometimes get corroded so you should also check and clean the contact surfaces(when checking you should check voltage on the back side not the fuse side as some times the printed circuit is bad.

 

Okay, so the brake light bulbs just needed replaced. I thought I had kept up on checking them better than that. But the tail lights are still out. I bought new bulbs but they made no difference. Re-checked all the fuses but found nothing new to report. No progress in the instrument panel lighting.

 

Check to see if you are getting juice to the rear connectors. If not you may have a bad relay. if you are getting juice to the connectors check with a test light(you may not have enough amperage) as chicking with a volt meter might say you have 12 volts but not enough amps to light the bulbs.I spent over a week with a similar problem and found it was the fuse boxes not transmitting enoufh amperage to the rear of the car (also cleared up dash lights directional lights and seat problems).If you fuse boxes are bad try to buy them at a salvege yard(bought mine from a pull a part for $20.00). just take your time and make sure you trace each wire correctly.