Engine Control Fuse 1 Keeps Blowing

[ddeadserious]

:pissed:

The Engine Control Fuse 1 is in the PDC under the hood, it cuts power to the Ignition Coil for sure, and I think it cuts power to the fuel pump, but I have the stock fuel pump wiring bypassed. So for me, it cuts power to the ignition coil, therefore no spark and no start. The starter and fuel pump function just fine.


Drove the Jeep for over a year, without issue.

Then the fuse blew a while back and I replaced the CPS thinking it was that and eventually found out it was the fuse.

I replaced the fuse and drove for a few weeks and it died again.

Replaced it again and drove for another few weeks.

Replaced it again and drove it until tonight.

Replaced it with a 50 amp fuse(should be a 30 amp) because all the auto parts stores were closed and we had one of those(they're the big honkin' ones).

It started up and ran for about 2 seconds and died.

Smelled burning, and the fuse was blown.

Any frickin' ideas? Anyone got a schematic or whatever that shows where that fuse leads?

[Mongo]

Jeep yj, tj, cj, xj, zj........??????

[Evil Queen]

I'm guessing xj....women's intuition?

[ddeadserious]

XJ, I'm sorry.

[MuddyPaws 3.0]

Make, model, year, motor, trans

Newb :hehe:

You have a short. Putting a bigger fuse in there will start a fire. But then you'll find the short.

[ddeadserious]

Make, model, year, motor, trans

Newb :hehe:

You have a short. Putting a bigger fuse in there will start a fire. But then you'll find the short.

If you're being serious, it's a 1992 Cherokee, 4.0, Auto(AW4).

I'd rather not start a fire, not bad a advice though.... I've only got PLPD insurance.

[MuddyPaws 3.0]

You sure it's fuse 1? I looked at the diagram and fuse one is a 20 amp normal size fuse.

[booblinker]

Is it this one?:flip::flip: http://detroit.craigslist.org/cto/783168883.html

[ddeadserious]

You sure it's fuse 1? I looked at the diagram and fuse one is a 20 amp normal size fuse.

On my fuse cover, it says Engine Control 1 for the big one that keeps blowing.

There's a small one on the other end of the fuse block named Engine Control 2.

[ddeadserious]

It's fuse #15.

Runs to ECM pin #3, which is marked as Battery. It also runs to the Auto-Shutdown Relay fuse and to the Fuel Pump Relay.

Guess I'll be running over some wiring tomorrow. Hopefully it won't start pouring on me like today.

[MuddyPaws 3.0]

Yes, 15 was the one I was thinking you were talking about.

It also powers fuse 4, 20 amp, in the PDC, for the cooling fan relay.

Wow, there are a lot of places it could be shorted. Look for chafed wires or places the harness could rub on things.

[Yota Bill]

if it is blowing a fuse that feeds other fuses, and the downstream fuses are not blowing, then the short circuit will be somwhere between the large fuse and the smaller feeder fuses...if the short was after any of those smaller fuses, then that one smaller fuse would be the only one to blow, not the main fuse...

[ddeadserious]

Yes, 15 was the one I was thinking you were talking about.

It also powers fuse 4, 20 amp, in the PDC, for the cooling fan relay.

Wow, there are a lot of places it could be shorted. Look for chafed wires or places the harness could rub on things.

My aux. cooling fan started acting goofy around the same time(not totally broken, no blown fuse, just acting abnormal) that I started popping fuses...

Yeah, this ought to be fun. Thanks for the help.

if it is blowing a fuse that feeds other fuses, and the downstream fuses are not blowing, then the short circuit will be somwhere between the large fuse and the smaller feeder fuses...if the short was after any of those smaller fuses, then that one smaller fuse would be the only one to blow, not the main fuse...

Good thinking, thanks.

[MuddyPaws 3.0]

if it is blowing a fuse that feeds other fuses, and the downstream fuses are not blowing, then the short circuit will be somwhere between the large fuse and the smaller feeder fuses...if the short was after any of those smaller fuses, then that one smaller fuse would be the only one to blow, not the main fuse...

You would have to look at the diagram but there are separate wires off the big fuse feeding the smaller fuses.




The cooling fan could be shorted. Unplug it and see if the fuse blows.

[Yota Bill]

yes, any of those short wires leading to the smaller fuses could be shorted, but the short circuit wont be after the smaller fuse...if it were, it would blow the smaller fuse first, and not get a chance to blow the bigger fuse..

the problem could also be minor overloading of each of those sub-circuits resulting in a big overload of the main circuit, but thats not going to be the case here, since he already put in a 50A to replace a 30A and blew it right away too..

if you have a schematic you can post, I'd like to see it...I might be able to help alot more with a schematic...

[ddeadserious]

Just checked all the other fuses in the PDC.

The IOD Fuse(Fuse 4) is blown as well.....

Came in to check the wiring diagram, back out I go.

[ddeadserious]

Erm.... Pissed.

I inspected every length of wire that I could see or that could have possibly been rubbing anything. I checked all the wiring that I could think of, and pulled off the wire cover on the ECM and checked the plug at the cooling fan and did all kinds of checking and couldn't find a single piece of wiring that looked suspicious...

Replaced the IOD fuse and the Engine Control 1 fuse, and she fired right up. I let her run for a few minutes and revved the engine up pretty good and it had no problems.

Now I suppose I'll be sure to keep a fire extinguisher nearby in my Jeep, and pray that the problem magically fixed itself.... Or I'll just wait until the 30amp fuse blows again and I'll get pissed again.


Anybody have a better idea? I'd love to solve the real problem, but I just can't find anything.

Thanks for the help guys, I've received little help from other forums(other than dodger889 on GL sending me a wiring diagram, which was amazing).

[Yota Bill]

just curious, what happens if you remove that IOD Fuse(Fuse 4) and then start it up?

it could be something with that circuit being incomplete (blown fuse) causing something to backfeed and overload the other circuit...

[ddeadserious]

Okay, so I'm about a foot away from beginning a part-out.

I did all the wire tracing I could. I got it all running and went and jiggled every connection and loom of wire I could see. I checked every length of wire that was even remotely near anything that moves.

The most I found was an open, live wire in the loom that leads to the headlight/turn signal/aux fan/ds horn, and I cut it off and heatshrinked the end thinking that might have been the problem.

I replaced the fuse and started it up three times and revved the engine and stuff.

I let it sit for a few hours and moved it out of the driveway later on in the evening... and it started up with no issue.

I went to leave for work this morning and it told me no.

Popped two fuses right in a row, just like last time. I don't even know what to do anymore.


This has only happened once while driving, and I'm thinking that was a fluke. It's something that mostly happens when it's starting - aka a sudden draw of alot of power going to multiple places.

I can't figure out how to get the fuse box out of its little cradle thing to check the wiring underneath.


I'm seriously so effing close to calling it quits on this Jeep and selling it ridiculously cheap.

[ddeadserious]

I just got the fuse box out, and took off the bottom cover and began cutting the loom open and tracing the wire that goes to that fuse.

Now I have to stop to help my girlfriend with some computer and job stuff.

I shall resume on Thursday.

Hopefully I'll find a chunk of wire sliced open or something simple.

[Yota Bill]

would still like to see a schematic if you have one you can post...I'm pretty decent with electrical troubleshooting...



maybe thats why I'm the electrical specialist in my shop, and techs from all over the state call me with questions? ah, just a guess...