2000 4.0 Grand Cherokee

[StevieC]

The computer is toast.

 

[jeep58]

Thank you !

 

[StevieC]

Good luck!

 

[SwampSurvivor]

Do the WJ grands have the unfused oxygen sensor wire that takes out the computer too? Or is that just the ZJ grands?

 

[jeepman3071]

Originally Posted By: StevieC
The computer is toast.


I wouldn't jump to that conclusion.

I've worked on many Jeeps and have NEVER seen a computer go bad on one of these. In fact I've seen more people replace computers because of recommendations like this and have it not be the problem.


OP: Do you have another battery you can try? Have you load tested the current one? Just looking at the voltage won't really tell you much. The one that died on me showed decent voltage also.

My dad's 1999 Grand Cherokee had the same issue. We could jump it, and it would run but needed the gas pressed or it would shut off. The gauges would go crazy, etc. Ended up being the battery. Chrysler electrical systems are very sensitive about battery voltage.

 

[jeep58]

Just got back from vacation in PA, going to check jeep out this week.

 

[JamesBond]

I would look into the cam and crank sensors before I replaced the computer.

 

[DoubleWasp]

Try another battery. Chrysler go ape feces wild on a bad battery.

 

[jeep58]

What would cam and crank sensor have to do with high voltage from alternator ?
Will try another battery but battery is from last year and voltage reads good.
Got computer and going to see if it works.

 

[jeep58]

Got computer out of car, however having a hard time getting computer out of bracket star head screws soaking in PB blaster, meantime can I plug the connectors into new computer without bracket mounted just to see if it works?

 

[StevieC]

You can just make sure the case is grounded in case the ground wire to the PCM has a problem.

 

[jeep58]

Ok I got the screws out, it has chrysler p/n p56041 638AD & motorola s/n 70A158CQIGB8 tags on unit, Is this the original computer and should I use a die electric grease on new one

 

[jeep58]

What type on screws Should I buy to use to screw back onto bracket. Stainless ? Cam I use some antisieze on threads?

 

[Trav]

You can get stainless Allen heads in SAE and metric from ACE hardware just match the threads there with an old one, yes you can use anti seize on them.
There is no reason you cant use normal hex heads unless there is a clearance issue.

 

[StevieC]

I'd use regular hardware that is simlar and just spray it with some Fluid Film before installing and after installing. By the time that coating wears off I'm sure the vehicle will be in the junker.

 

[jeep58]

Ok Put computer in jeep works great so far, Did not get chance to drive it but no miss idles good volt meter on dash working, put in gear good, put a/c on good. Hope the rebuilt computer is going to be ok it has a 1 year warranty I think that it was the original computer in jeep. Thanks for all the help!!

 

[StevieC]

Originally Posted By: jeepman3071
Originally Posted By: StevieC
The computer is toast.


I wouldn't jump to that conclusion.


See above... You were saying jeepman3071...

All joking aside I've seen so many in this era be a problem that is why I jumped on it after just a few questions...

 

[jeep58]

There were to many things wrong with the jeep, computer seemed very likely being the charging on the battery was very high and the voltage gauge just stops working, Thanks SteveC

 

[jeepman3071]

Originally Posted By: StevieC
Originally Posted By: jeepman3071
Originally Posted By: StevieC
The computer is toast.


I wouldn't jump to that conclusion.


See above... You were saying jeepman3071...

All joking aside I've seen so many in this era be a problem that is why I jumped on it after just a few questions...



Glad the OP got it fixed and hopefully this permanently fixes the problem.

Stevie the reason I quoted your post was because I've personally seen people spend hundreds of dollars on replacement computers which were not the issue. Always best to start simple.

 

[Trav]

Originally Posted By: jeepman3071
Always best to start simple.


When dealing with an unknown I learned start with the parts that are known to be bad then move on to the cheapest possibility if you are going with the shade tree lets throw some parts method of diagnosis.