I just bought a 1998 jeep cherokee, the engine starts and runs just fine. The windshield had a small leak that led to some of the electrical components inside the dash rusting out. After removing the headlight switch alot of stuff started to work again. However when I start the engine it all stops working. No power windows or mirrors no interior lights no wipers nothing but a running engine. Shut the engine off and it all works again. There is a small silver box under the dash on the left side have no ideas about what it is for but it has rust on it as well. Bought a new headlight switch and brake pedal switch, can't install at the moment because the jeep is in Florida and I'm in georgia.
Any help would be greatly appreciated and thanks for taking the time to read my post.

 

That small silver box on the right side of the driver's footwell up under the dash should be your transmission control unit. First thing I'd do is check all your ground. By check, I mean actually disconnect them, clean them, and reassemble. There's thread on here somewhere showing the location of all the grounds with pictures.

EDIT: See post #20 of this this thread to find all your grounds.

 

I'd actually suspect the ignition switch is bad, possibly not returning to the run position after starting.

 

The ignition does stick a little bit, I have the dash removed at the moment was in the process of checking the grounds before I ran out of time and had to go home. Will definitely replace the ignition switch now.
Thanks for the help and I'll post to let y'all know of it worked.

 

Before firing the Parts-Cannon at it, clean all of your grounds. You can often solve the problem this way. Cruiser54 has a website with instructions and clear photos on how and what each one does. This vehicle is HEAVILY dependent on crisp, clear grounds.

 

You can find pics of all the grounds in my sig, #1.

Can't do much until you can get your hands on it and do some testing.