jeepct

Not being careful under the hood, i shorted out a power wire and killed my jeep. I discovered the positive power wire had continuity with the vehicle ground. I followed this back to the relay box. With the front power wire disconnected from the box, i found that every single fuse in the relay box was connected to/had continuity with ground. does anyone know what could cause the whole box to be shorted to ground? Thanks in advance!

jeepct

Update: The wiring isnt shorted out as I had thought, that was only because my door was open and it read low resistance. A little more info: The jeep has power at the PDC but no dash nor interior lights come on in any mode. The relays for the fuel pump and ASD appear to be clicking in some way, and sometimes the two relays will make a humming sound when the vehicle is switched off. Both relays have been tested and have continuity when powered.

fb97xj1

Check the IOD fuse in the PDC. Should be marked on the PDC cover. I blew the IOD when messing with the TCM and lost the courtesy lights. Check the JB for any blown fuses too. I think #16 is for the lights? Check all of them while you are in there, just to cover them. And relays shouldnt do anything with the engine off. Never heard them hum either. Not sure whats up with that.

jeepct

Thanks for those suggestions. I went back and checked all the fuses and relays in both the PDC and junction box, and found nothing was broken or burned out. I should mention that nothing comes on when I turn the key, dash and motor are soundless. Battery has been tested and is fully charged.
Some interesting things I found in the fuse box: Since it is a 97 it has four large relays for the starter, fuel pump, ASD, and Cooling Fan. Each relay has four pins, 30 85 86 and 87.
I tested another Jeep and it appears that pin 30 should always read 12 volts, and the others should be zero until the Jeep is turned on. When the engine is off but the key is in the on position, pin 85 on all relays besides the starter comes on. I imagine that the starter pin 85 would come on when the key is turned to start. This was a 2001 xj.
My 97 4.0 xj got some different readings. In the off position, I had 12V at all pin 30s. But on the fuel pump relay and Cooling fan relay I had 12V at pin 87, and at pin 85 on the starter I also had 12V. When the key is switched to on, all pin 85s become 12V as expected.
What could cause my starter pin 85 to be on? I would think that would keep the starter always on.
Why would pin 87 on the fuel pump be on? Wouldn't that defeat the purpose of connecting the fuel pump to the pin 30 to power it? Same with the cooling fan?

Just to reiterate, the fuses and relays in the PDC and JB are all working. I just find it odd that the entire Jeep is dead, not even the engine bay light will come on. No fried wires in the PDC either.

jeepct

Result: The grounds were bad. If anyone's looking for a solution for this in the future, check your grounds. They make a he** of a difference.
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jeepct

Thanks fb97xj1 for getting my Jeep back on the road