Brian78

Why is it everytime I turn my key to start my 95 jeep cherokke sport it blows my 30 amp maxi fuse under the hood. checked the fuel pump it's good. My smaller 20 amp fuse stays good under the hood and sounds like the relay is clicking? No seen bare wires anywhere....Please help.

freegdr

theres a short some where...

Brian78

Where would be a good place to start

freegdr

seeing what all that fuse powers is it a big fue or little fuse

F1Addict

This is the part that sucks... because it could be anywhere. Does it only blow when the starter is engaged or will it blow with the key in the "ON" position?

freegdr

this ones all yours...lol...

Brian78

it does it as soon as you hit the on doesn't even make it the engage the starter

Brian78

If I put a new fuse in and don't turn the key the fuse is fine, and it only blows that fuse. No other

Brian78

I know the power wirefrom the pump is good to the rear seats. And volts seem right from the battery to the relay under the hood.

F1Addict

Ohhh no

Well, that 30A maxi-fuse controls the following:

Engine Control Unit (ECU) - Fuel pump, injectors, ignition coil, oxygen sensors, generator field, and auto trans controller (TCU).

That is where I would begin my search. The bottom line is that there is a short to ground somewhere. It could be an internal component on the ECU or TCU but the much more likely cause is a bare wire. Check the most likely places around heat sources (engine and exhaust) and look for melted looms or charred insulation, especially on O2 sensors. The TCU is under the passenger side knee bolster. Check the undercarriage near your fuel pump. There is a PDF link to the power distribution of 93-95 XJs on this page, which might help in your search.

Brian78

What gets me is wife was just driving down the road and it blew then. I thought it was the fuel pump so went and bought new one. Have already checked o2 sensors and wires around the injectors. Don't know what generator field and auto trans controller is?

rdeskater

looking for an update, same problem on my 94 did you fix it? where was the source of your problem?

Brian78

No still trying alot of trouble shooting. I know from my pump to where my wires come through the back seat are good at this point. Then they run off and not sure where they go from there. Then they come back up by the fuse panel and I think they run to the emc? Not sure yet don't quote me on that. Now from battery side battery is good, wires to main fuse block good, 30 amp fuse stays good as long as you don't turn the key, then the relay is good, and the little 20 amp fuse is good in main fuse block under the hood. Pump works because I ran different power to it. but still at a loss for what keeps blowing this fuse. The 30amp maxi does run more than pump though, it also runs.... Engine Control Unit (ECU) - Fuel pump, injectors, ignition coil, oxygen sensors, generator field, and auto trans controller (TCU).

Continues to be a really bad pain in my bad back...Wires don't look burnt anywhere that I can see, so guessing it is shorted out on another component. Really at a loss seems it blows before you can even test other things.......you find an anwser, PLEASE PLEASE PRETTY PLEASE POST IT HERE!!!!!!!!!!

tiwvr1

Maybe start unplugging stuff, like the alternator or pcm to start, turn key and see if it still does it. That MIGHT rule out that particular component.

freegdr

check down stream o2 wiring harness for bare wires around transfercase area very common problem gets rubbed thru and shorts to ground