[junkzj]

ok guys help me out here, 93 gc 4.0 when starting the jeep of a morning it will crank and crank until the battery is dead, the only way you can get it to start is to turn the key to the run position and let it sit for anywhere from 5 to 30 seconds. i have noticed that if you just jump in and start cranking it wont start. if you turn the key on and wait for the check engine light to come on and then go off it will fire right up. then and only then it will start, i can't figure out why it doesn't come on as soon as the key is turned on. almost like waiting for a diesel to warm up the glow plugs. I also noticed that as soon as the check engine light comes on there is a buzzing sound that only lasts for a second coming from under the hood. there are no codes stored, and it runs fine once it starts. :???:

 

[AndyZJ]

Maybe your security auto shutdown relay is going on and off and that is what is causing the issue. Turn the key to the run position and then go under the hood and see if you can locate where the buzzing sound is coming from. I wonder if it is from the relay/fuse box under the hood because what you are describing is an auto shutdown relay issue.

 

[nick_n_ii]

I just went through the same prob, replaced everything before I found it was my Computer dieing, replaced it no more problem

The check engine light on and off thing is the computer doing a self test, if it "glitches" it will restart the sequence and not let the vehicle start till it gets it right...

Replace the computer and your prob will be all gone...

 

[junkzj]

the auto shutdown has crossed my mind, Im gonna check that as soon as I can get someone inside to watch the check engine light while i try some stuff under the hood. also thought about the computer getting ready to take a dump, gonna check first before I start spending $$. I'll let you know who's right when I figure it out. this jeep used to be a v8 and I swapped in a 4.0 from my old jeep that I rolled, and it never did this. it started after I did the swap.so that leads me to think that I screwed something up in the process.

 

[junkzj]

alright, finally got a code out of it, and only got it once, code 54, this leads me to believe its a crank sensor from what I've read, it is getting worse. taking longer for the light to come on after you shut it off. took about 15 minutes last time I tried, as long as you don't leave it shut off for more than 10 minutes at a time, its not an issue, but I can't run out and start it every 10 minutes! let me know what you all think.tested the auto shutdown relay.... not it. crank sensor, pcm, or???? :???:

 

[OverkillZJ]

CPS, common problem on these motors.

Suggestion someone replace the ECU based on his symptoms is just dumb...

 

[nick_n_ii]

CPS, common problem on these motors.

Suggestion someone replace the ECU based on his symptoms is just dumb...

You must be referring to me, I replaced the Crank Positioning sensor, the Coil and all the body to motor ground wires, Along with getting rid of the Security Modula... before I replaced the Computer so Piss off on that being Dumb cause it fixed my problem...
And it vary well might be his....[/b]

 

[AndyZJ]

I think what OverKillZJ was trying to get at was a computer can run you anywhere from $100 at a bone yard to a couple hundred at a dealer compared to a sensor or relay being a only a few dollars. Its starting at the easy problem first and working towards the harder problem. That's why on trouble trees for dealerships they have "replace the ECM" at the BOTTOM of the list. So telling someone to spend a hundred bucks is "stupid" if a cheaper sensor could repair it. Also like was stated, the cam sensor is a common problem on the 4.0L, too bad we all missed it, but i hope that fixes the problem for you.

 

[nick_n_ii]

I know the ECM is the most costly part, It's just I went through all the same things just to find after all else was replaced that it was bad, so in the long run I could have bought 2 ECM's for what I have into my fix..

Hopefully his is simple I just know I fought mine for well over 3 weeks till all that was left was the ECM....


Good Luck....

 

[junkzj]

alright borrowed a coil, distributor, and crank sensor from a buddy tried all of them, nothing worked....so its looking like the computer. found out that it also won't kick the fuel pump on until check engine light comes on, along with the lack of ignition. I'm pretty sure I've covered all the bases.found out clicking/ buzzing sound is coming from the computer along with a high pitched squeal kind of like when you turn on a tv. [smilie=censored.gif]

 

[AndyZJ]

I just want to make sure you cleared the CPS code after putting the new CPS in before trying to start it again.

 

[junkzj]

it cleared itself, it only showed up once out of the ten times I checked the codes.

 

[junkzj]

and the problem was............................computer. borrowed one from a buddy and it fired right up, thanks for all the help, now everybody can ease up on nic_n_ii. luckily I have lots of buddies with cherokees and parts cherokees and I didn't actually have to buy anything, just had to spend time on it. but thanks again for all the suggestions [smilie=bowdown.gif]

 

[nick_n_ii]

Good to hear it's all fixed now.. [smilie=bal_cool.gif]

 

[AndyZJ]

and the problem was............................computer. borrowed one from a buddy and it fired right up, thanks for all the help, now everybody can ease up on nic_n_ii.

Its good to know you fixed it. And the suggestion was only that going straight to the computer would be the most expensive option, but being that you had friends with working cherokees to borrow parts from it didn't make a difference and didn't cost you any money to just change parts until something worked.