91 Cherokee blowing ECU fuse

Jun 02, 2005 2 Replies
K

A week ago I was driving home. I went up a big hill and the truck just died and wouldn't restart.



I called a friend who towed me back.



When I checked things out, the ECC fuse (30A in the engine compartment fuse block) was blown.



I replaced it and the truck started right up.



I let it run for a few minutes and went to move it up the drive way. As soon as I "goosed" the gas, the fuse blew again.



This time I looked more carefully and noticed the plastic square tube that carries the wires to the fuel injectors had come off it's mount and was lying across the top of the motor.



I inspected it for any wires that might have arced (didn't find any) and put it back.



I then replaced the fuse and it started again.



Now until I can figure out what happened, I'm afraid to take it out of the driveway.



My question.



Are the inputs to the ECC (CPS, etc) protected in any way? or could an intermittent short in one of the sensors cause the ECC fuse to blow (nightmare). Or is this more than likely a bad injector. The Haynes only shows the system in block form and didn't elude to fuses or links for the inputs.



Any help would be appreciated as I want to start driving this truck again



thanks


-bob-


This E-Mail is certified to be Virus Free by Symantic® Norton Anti-Virus Suite


Vote
Twitter Facebook LinkedIn
S

You didn't tell us whether you tried gooseing the gas... I'm guessing (gooseing?) that you did, and that it didn't repeat the performance.

Did the injector wires come close to the secondary ignition wires? There's a condition called latch-up where a FET junction can conduct catastrophically given the right shock... maybe this happened. Otherwise, just kill a chicken, spread the blood around the Jeep on the ground while saying the appropriate mumbo-jumbo, and take it out for a test drive, preferably with a cellphone (or ham radio!) along.

40 amps doesn't normally flow to ground without making some big holes... frankly, I'm suprised that the ECU worked after replacing the fuse. Every input and output in the computer chip is protected with a diode to ground, and a diode to hot... perhaps these saved you. Verify that you still get ignition advance... it might be in limp-along mode. __ Steve .
Vote
Twitter Facebook LinkedIn
M

You have a dead short some place physically hot likely that tags when the engine twists under rpm load.

I would be looking at the O2 sensor wires, especially if any are near the cat and the 4x4 wires that go to the transfer case and cross near the exhaust.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"KoRn Kid® (Child of the KoRn)" wrote:

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required