cbpatten

jeep is deep off road and not starting after running great attempting to fix/retrieve and trailer it today,

1998 Jeep Cherokee Sport 4.0 Auto Trans(police edition) 175k well maintained stock minus small lift and tires, and has not had issues at all of recent.
3 in lift 31x10.5s

While driving in 4x4 full time the jeep over the past few years on a hand full of occasions my jeep would pop out of full time 4x4 and the jeep would loose power to the engine and shut down but all electrical interior stays on dash lights all go off like ignition position 2 when starting the xj. On multiple occasions off roading over the past few yrs this has happened, i would turn the key off, put it back into 4x4part time and fire the jeep right back up, if the engine is running a little hot here in AZ it may take a sec to cool of the injectors in-order start but it fires up.
This most recent time i was going up a steep,rocky, gravely, dirt hill in 4x4 low and in 1-2 on the tranny, hit a big rock and the same thing happened but this time it not firing up. and the guages are no longer registering when i turn the key into position 2.... Im going out there tomorrow with parts and tools galore but could use some ideas.
ive check fuses and connections, im getting fuel pressure and can hear the pump, it cranks but is not getting any spark.

Im going to start with a neutral safety switch being i rarely use 1-2(tranny), i have a good cpu/pcm/ecu that ill try, a new crank position sensor, and checking grounds.... does any one else have any ideas???

Jeep is deep currently stuck off-road attempting rescue mission tomorrow. Please help if you can with potential trouble shoots

jordan96xj

Take a spare ignition switch with you. Or at least have the tools to remove the existing one to inspect (tamper resist torx).

Take a test lamp, and a couple of ground wires (24-36 inches of 8-10 gauge wire with alligator clips at the end). Make sure you have your multimeter (if you know how to use it).

The fact that you get no internal dash activity makes me think that the ignition switch is getting shocked and killing the ASD relay (stopping ignition). Or you are bouncing the battery so hard that a battery connection is failing. So make sure you have the stuff to clean that up as well.

Good luck, and please let us know how it goes.

jordan96xj

Last thing you want to hear about right now is me, but coincidentally, my XJ also stalled on me for the first time ever this weekend. While the wife was on-board for the first time (she had never been off road before)...back in the sticks...while in a mud hole! In my case, the fuel system had either vapor locked, or sucked a slug of air. Once I got that cleared out, I got it running again. It sucked, but wasn't too serious at least.

cbpatten

Went out to try and get it out of the woods but failed. Swappedd the ECU and it fired right up but died again after a couple miles ehen i went to shift out of 4x4 low after a steep crawl and the spark died leaving all lights lit up on the dash. Turned the key off and back on to find no working guages again but lights and everything else work. No spark again and I'm worried I'm frying ecu's... Any ideas

Fuel pressure is good, no vapor lock, it's a spark issue. Checked fuses and connections. Nothing worked minus the back up ecu for a.couple miles.

CoffeeCommando

Bouncing around isn't easy on old ignition coils. You have the one on the engine block. I hope noe one has messed with it in the past and removed that metal bracket that mounts it up and away from the engine block. That helps reduce heat and extend the life of the coil. If that's attached to the engine block, I would be suspicious... but in my experience those either work 100% or not at all.

Since you said shifting with the 4x4 lever seems to cause issues, get down there and make sure there are no exposed wires. I recently had my tach reading shooting all over the place. The wiring harness had been left loose when I was down there previously and the rotation from the shaft on the sharp corners ate through wire loom and the wires shorting out the speed sensor. Luckily it was only 1 wire, the positive or signal wire, so touching the metal was grounding it to the body. I just taped it up real good and secured it away from the drive shaft, problem solved.

If I had had two wires damaged I would have had to get invasive with either soldering or doing some splicing, up above the transmission. Not an ideal spot to be doing any of that kind of work. If you do find damaged wires that are touching themselves causing a direct short to the ECU and it's not an important sensor required to operate the transmission, just find a way to make sure they aren't touching until you can get some place where it's easier to fix it. Having a 4.5" lift and 33+" tires really makes working on stuff down there a lot easier.