I have a '97-XLT, 2WD with a 4.6L in it. Just purchased about 2 months ago. My neighbor called and told me one day at work, that he saw the dome light on inside the truck, and that the brake light above the rear glass was on as well. He said about 5 minutes later, the lights were off. I came home assuming the battery was dead, truck started right up. I assumed the door wasn't shutting well, and the door lights were staying on, so I sprayed the hinges down with WD-40.

I didn't start the truck for 4 days, went out, battery was dead, would not charge at all, so I assumed it was an old bad battery. Replaced with a new battery that day, everything seemed good. Go out to start it 2 days later, the new battery is dead. So, last night, I jumped it off, then removed the fuse that goes to the dome light, door lights, and power windows. I try to start it today 24 hours later, and it fired right up.

I thinking a couple of things but I wasn't sure. Is there possibly a bad relay causing the truck to suck the battery try? Or, is the altenator going out, and it's time to replace with a new one? I just thought it was weird that the dome/door lights came on like this in the middle of the day, when no one had been in the truck for 2 days the first time this happened. I appreciate any help you can give, thanks.

 

Get the alternator tested at a parts store. Auto Zone, Advance, stores test for free with the alt on the truck. It looks as if you have a short in the courtesy light circuit

 

i dont think its the alternator. it appears to be related to the fuse circuit you pulled. figuring out what is causing that can be difficult. i would leave the fuse out and see if anything else causes the discharge. could be a door switch, or could be a grounded or corroded light socket, etc... make sure its only that circuilt and not more wide spread.

 

I'll leave it out for a couple of days, and see what happens, hopefully that will pin point the problem a little.

 

Sounds to me like the the door switch is sticking. Spray WD-40 into the switch area inside the door frame. It's pretty common for these switches to stick.

 

Your Main light switch/Dimmer is probably intermittent.When the rehostat(Dimmer) is turned all the way up,and past that to the 'Click" it turns on the dome lights,and bed light.I suspect THAT switch is either internally damaged,or you have inadvertantly left it in the "interior light" position.
My suggestion is"work it" up and down a few times,and feel for the "click" at the uppermost position.If it sounds normal,and the feel of the click doesent change noticeably,Id say thats not the problem.If it feels spongy going into the detent position,then the switch/rehostat is likely toast.
I think your Alternator is probably fine.

 

You can use WD-40 as a cleaner, but it has no lasting lubrication value. Use white lithium grease instead. All WD-40 does is give you some quick lubrication, but later on it just attracts dirt. A heavier grease will do a better job and it stays where you put it.