ELECTRICAL HELP PLEASE

I have a 91 XJ with some kind of electrical malfunction, I haven't seen before. The interior lights stay on all the time unless the parking lights are on wheather the jeep is running or not. If I turn the interior lights on with the dash switch or by opening the door it pops the taillight fuse. I am thinking that the headlight switch might be bad, but am looking for other ideas as well. Any help or suggestions very much appreciated. Thanks in advance.
RR

You can test out the switch and then the wiring that connects to the switch with a multimeter (volts/ohms). Please see PM for details.

OK, I replaced the headlight switch cause it had to come out to test anyway. Changing it did not fix the problem, but in further diagnosis I find the alarm system is not working either. The power locks are OK, but the security light on the dash never comes on. I know the dome lights had to go off before the security engaged when everything worked. I tested the rest off the fuses and they're good....is there a timer in the alarm system or am I missing something?


RR

break out the vom and start tracing wires. You gots a short me thinks.

The tail light wire is shorted to the interior light wire between the interior lights and the switches for the interior lights. They interior light switches make the lights work by completing ground. When you open a door, it grounds out the tail light circuit. Have you checked for melted wires around the interior fuse box and right behind it? You need to trace the tail light wires. The 2000 has separate fuses for left and right tail lights. If your model does too, that will help you trace. Pull the bulb out of that taillight and test that wire with an ohmmeter. That wire will show continuity to ground when you open a door, but it should not.