Hi everbody!

Last week my 1996 XJ 4.0 died while driving. The cause was a blown 30 amp fuse.
I went ahead and replaced it, turned the key on and without cranking the motor it blew again.
So i suspected a wire touching ground somewhere.
I disconnected the fuel pump and both o2 sensors and the fuse would still blow.
All the wiring under the Jeep is fine and both o2 sensors wiring is fine too.

Then i disconnected the ECU and the fuse would not blow when turning the key.
I then hook it back up and the fuse still doesnt blow, but now i the ecu doesnt seem to be working at all!!!
To make things weirder the fuel pump now runs nonstop when i turn the key on,
usually it would run for a second to build up pressure and then stop until id fire up the engine
but now it just keeps going until i turn off the key.
The first thing that comes into mind is a stuck fuel pump relay, but the more important question is,
what usuall causes the relay to close?? the ecu??

Anybody had this before? Cant afford buying a new ecu without being 99% sure.

Also, i am not very good with electrioncs, my ecu has p56041 200 written on it, its an aluminum casing and has three plugs.
I was wondering, are these 4.0 ecus all the same? Can i install a ZJ or YJ 4.0 ecu in my XJ?

Somebody please help me out here.

Thanks alot in advance!

 

Anybody?

 

Check a post I started on 4/1/12.Fault code P01695.A guy named CCKen gave me alot of info about fuel pump power supply plus some good diagrams.I had to order a PCM yesterday from a site called Auto Computer Exchange.net. Paid $152.95 plus $25.00 for shipping.

 

The fuel pump relay is grounded through the ECU to allow the ECU to turn it on/off.

I've seen a couple ECU/PCM modules short like that. I suspect there are filtering/protection components on the 12V power input that may short to ground, but can't prove it as they're soaked in epoxy and can't be disassembled without destroying them.
I'd get one from the Salvage yard off the same model/year Jeep if possible. If you have an automatic...get one from a donor with an automatic, etc. Others may work, but a direct replacement is less worry, IMO.