extremeodd

So I have a 96 Grand Cherokee Larado that won't start (~200k miles). It cranks and sounds like its catching but wont run.

When the key is turned forward the gauges do nothing and nothing gets power including the radio, blower motor, windows, etc. I've read that the CPS can cause the no gauge/start issue but unplugging it and turning the key to run still results in no gauges.

I've gone through the fuse block on the passenger side and the fuse block under the hood and nothing is blown. I've also tried playing "musical relays" (swapping them around) with no luck.

Despite my best efforts with googling, everything I come across involving no gauges is either a bad fuse or bad CPS and that doesn't seem to be my problem. I've also tried unhooking the battery, unplugging the ECM, backing the two torx screws out about half way (supposedly they short on the board) and plugged it back in which did nothing. However I did notice it is quite rusty on the top part of it, is this a failure state of the ECM?

The ignition switch is good, I manually jumpered the connector and completely bypassed it and there is still no accessory power/fuel pump/windows/wipers/blower/power locks/etc. Also she seems to be getting spark as it ran for a moment when this first happened, as if it was running off the residual fuel pressure in the line before running out.

Any ideas?

I should mention that before this happened I was tooling around in the snow doing donuts and whatnot and the jeep seemed to occasionally almost die like the battery came unhooked but would continue on. Also today after letting it sit for a few days the battery was dead so I hooked a charger up to it and it came to life so I drove it around to charge the battery and I noticed when I cut the wheel hard to the left and floored it (fishtailing on gravel) it died for a moment and came back. After I parked it and removed the key it resumed the failure mode of nothing working. Unhooking the battery for a few mins doesn't seem to help.

dave1123

Is the battery secure and not moving around? It could be flexing the main power wire to the PDC (fuse/relay box under the hood.) That wire supplies all power to everything except the starter. Look for a bad connection inside the battery clamp. Without a good clean 12v supply weird thing can happen.

extremeodd

The battery is bolted down very solidly however the terminals aren't the factory ones. Ill try tearing apart the positive and reclamping the wires to see if that helps.

EDIT: So I checked out the terminal and both wires were in there quite solid. When I went to turn the key the battery was dead (again) so I threw the charger on it on the 50 amp jump setting and wouldn't you know it, it started again just like yesterday. So I drove it around the neighborhood to charge up the battery and when I got back to the house I pulled the positive terminal. Now in a few hours Ill go out there again and reconnect the battery and see if she will start.