Time to replace the PCM?

Yeah there is always a danger that when you swap out a unit like the PCM you introduce some new issue ie. you bump something, knock a connector loose etc.

Been there done that in my 34 years of fixing IBM and Hitachi Mainframes when I was young!

Billwill said:

Yeah there is always a danger that when you swap out a unit like the PCM you introduce some new issue ie. you bump something, knock a connector loose etc.

Been there done that in my 34 years of fixing IBM and Hitachi Mainframes when I was young!

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Mate... you are spot on... I must have knocked C108 when removing/installing the PCM.
After spending ages removing the heat shield on the starter to get to the connections I found no power to the starter. Main feed was fine. then traced back and found c108 was loose. Secured it and all is now good, except for some smoke coming off the LH cat and exhaust. Guessing some oil has dropped on it or unburnt fuel in the cat itself.

Thanks again for you help and wisdom Billwill

Great!

At least you now know your way around the KJ.....hopefully you will have many years of enjoyment with your Jeepie!

Hi PaulP38a,

I found your thread after running into similar issues as in your OP. It seems like the PCM ended up being the problem (outside of the no-crank issue)?

FYI, my symptoms are that my 2002 3.7 A/T Jeep Liberty Limited (in Canada) had a rough idle for a couple seconds on 3 occasions during the 6 weeks before the rough idle became consistent one evening. I am about to start checking wires, but I had coil codes on cylinder 1 and 2, and have found that cylinder 4 also isn’t firing in the troubleshooting process. Started with moving coil packs arounc and the problem didn’t follow the coil pack. Weird thing is that I am not getting spark on any of the plugs when I remove them (well-grounded when testing), but I am getting voltage to the 12V side of the pack. I just replaced the plugs yesterday with the the correct NGK ones (gapped properly too), but the rough idle is still there.

I’ll check the coil packs again and then move on to check grounds (power ground to PCM, engine and battery ground as BillWill said) and then wires.

The fact that it came and went 3 times before points to a common issue being the culprit. Just hope it is ground and not a wire (that I have to find) issue nor the PCM…

Billwill said:

Use approximately the same gauge wire as the wire you are replacing.

While that original wire is now "hanging in mid-air" because you cut it off at both ends...place your Ohmeter onto that wire and measure for any conductivity to ground....make sure you are not using bare hands while doing this as it affects the reading.
If you do get some form of resistance reading then this means that the wire is scraping to Ground or to some other random wire!

I have replaced about 15 wires using this process after a frontal collision on my 2002 Export Diesel!

If replacing the wire has no effect...solder the original section of wire back in place using Heat-shrink Insulation.

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Don't use solider anything electrical that is subject to vibration as thats a stress point that can break because of stiffness, use crimp connectors and heat shrink over it.