Here's a mystery question

Last night I went out to get something from my XJ and noticed the dome light was on. The door switch hasn't worked in 3 years and I knew that wasn't why it was on. I then checked to make sure I didn't turn it on with the light switch and I didn't since I wasn't driving it at night. Why would the dome light be on without being turned on? It has been between 2 and 19 degrees here for the last 2 weeks. Could that cause the light to go on?

My temporary fix was to just take out the bulb. Anyone have a real clue? I haven't checked to see if my battery has exploded yet this morning.

is your dome light the one that is turned on by the headlight switch (turn instead of pull deal?) if so, it is possible that your headlight switch is going...

The dome light uses a switched ground to turn on. There are switches at every door and at the light switch. If any of the switches or wires going to them is shorted to ground the dome light will come on. I would check to see if any of the connectors or switches at the doors are bad. I had to find a problem on my neighbors XJ that the dealer gave up on, their dome light would come on when they went over bumps. I found a very small knick in one of the door switch wires that would short to ground when they went over bumps.
Dave

check the back hatch. this happened to me once, and the hatch wasn't shut all the way.

Reminds me of a story...

Had a buddy who was able to buy a late 80s (rear-drive) Caddy for a fraction of the price, with not more than 80k on it. Good shape, etc. But it wouldn't hold a charge. No one could fix it. It was drawing amperage all the time, and short of disconnecting the batt, no one could fix it. One night, while in his dark garage, he noticed a faint "glow" from beneath the dash. There was a pen stuck in the glove box door, keeping the switch from getting tripped.
That bulb was about 800 degrees. It had been on for weeks! Prob fixed, he sold the car for about $2,000 more than he bought it! Killer cruiser ride.

i would start by checking the door switch........you said it hadn`t worked in a while.....the wire(s) may be loose or totally off and getting some connestion....also try "jiggling" the other switches if another one is going bad it may be stuck in the on position......

If all else fails, try taking up the drivers side carpet. Wife had an 87 that had a dim dome light on occasion. Also noticed, the dome light fuses periodically burnt out. The cables under the carpet were chaffed and the splices were green from corrosion. The moisture in the carpet padding and the chaffed wires, made for some strange electircal problems on occasion.
Even if this isn´t your problem it´s worth a look anyway, have seen the same thing on many Renix XJ´s. Some new splices (soldered) some tape (or shrink tubing) and silicon to waterproof, a piece of plastic cable channel and moving the wires as far left as possible, will help prevent future problems.