I'm trying to diagnose a strange issue with my 2005 G. It seems to have some intermittent electrical issue that has made it rather frustrating to troubleshoot. When driving the car can and will spontaneously shut down without warning. It may at times stumble, however more often than not it completely cuts out. The only codes that that I've pulled prior to this taking place is P2135, TPS, accelerator pedal position voltage mismatch. This led me initially to replace the throttle body, which appeared to resolve the issue for some time. Thereafter the issue reared its head once more leaving me stranded for some time. When it cuts out it will not fire back up, it is almost as though there is no spark- although I haven't confirmed this. Unplugging and re-plugging the ECM seems to often momentarily resolve the issue, or at least reset the system allowing for start up, from which I can limp it home.

I began to suspect the IDPM so I went ahead and replaced this, although the used unit I received appeared to have some previous water damage..I'm not sure the integrity of this component. Interestingly when removing my old IPDM there was a LOT of water within and I could here relays being tripped when moving it. In this process of troubleshooting I noticed something VERY interesting, moving the ECM and or wiring harness seems to directly manipulate the idle/throttle, see here I assumed there were some faulty ground connections, I checked both body grounds and they were fine.. Moving individual wires to the ECM/ECU harness also seemed to have no effect. Once again this seemed to resolve spontaneously for some time, ~ 1 week.

Today I got in the car and began driving to work it once again cut out. Turning the ECU/ECM elicited the same behavior. I'm a bit confused about what to do test next. I do have a spare ECM that I could throw in it,it would need to be programmed to my keys by the dealer...but might be one option. I also have a pedal sensor en route...Hoping I have this up and running well by the weekend in case I need to escape the impending hurricane- I live in NC on the coast.

Thanks guys for any suggestions!

 

I strongly suggest cleaning out the rainwater gutters and installing the factory plastic battery box and lid to protect sensitive electronics from getting drenched in water.

I also recommend disconnecting both ends of each battery cable (including body ground) and cleaning the termination points with a brush and applying some anti-oxidation grease.

Lastly, jiggling or moving components and having things run better (or worse) typically means a damaged connector or wire. Try to determine if it's the harness or the wire and get it fixed. Accidents happen when your vehicle mysteriously dies and you lose power steering/brakes/indicator.lamps/headlights.