DropTrooperZim

Hello all,

New to the forum but have been reading posts/threads for years and have been a Jeep Cherokee Owner since 2005. As a daily driver, I currently own a 2000 XJ, 4.0, 4WD, auto trans, all stock, 235,000 miles and I change the oil regularly. Past few months the CEL has been off and on randomly. Usually comes on in the morning and idles rough, hesitates and either sounds like its mis-firing or jumping gears, and wont accelerate for crap. When I start the engine with the CEL on it has an immediate high RPM jump to 1300 or so then will drop to the normal RPM range when I put it into over-drive. When I come to a stop it sounds like it stays in a high gear too long and stays at a high RPM for a few seconds before sometimes dropping below 1000 RPM. 50/50 chance the CEL will be off when I drive it home at the end of the day then it starts all over again the next day. When the CEL is off, it runs like beautifully. No acceleration problems, no mis-fire/gear shift sounds.

For some reason, the key trick doesn’t work for me to read codes. I’ve had the CEL read at a local shop and most codes are related to TPS and voltage. I had one code read P700. I’ve reads threads about related issues and codes. I’ve cleaned the throttle body and IAC. I’ve replaced the TPS. I’ve replaced the TPS connector/pigtail. I’ve replaced the change air sensor. I’ve replaced the CPS(crank). I’ve replaced the clock spring. I’ve replaced damaged CCV lines on the valve cover. I’ve checked the grounds (all I think). I’ve checked all fluids which appear to be at appropriate levels and color. I’ve replaced the spark plugs and ensured the gaps were gauged correctly. I’ve removed and cleaned the fuel injectors and replaced the O rings before re-install. I was getting a high voltage reading from the TPS sensor wire(middle #2 of the 3 wires), maybe there was a short/crossed wire somewhere. So instead of unwrapping all the wiring harnesses and wrappings to look for a damaged wire, I bypassed the wiring system and wired the TPS sensor wire straight to the PCM(C1/Black-23) and TCM(17). I did the re-wiring at night and drove it immediately after the job was done and had no CEL and it ran great! Next morning, CEL and associated problems continue.

Im planning on getting the CEL read again today. Not sure what the problem is. Could it be a bad PCM and if so, why did it go bad?

Thoughts?

Thanks in advance.

DropTrooperZim

Just had the CEL read and the code is P0122 - TP sensor circuit low input

Radi

Sounds like there's still a problem in the harness, perhaps the +5V line that supplies the sensors is intermittently shorting. Did you re-wire that too, or just the signal line?

DropTrooperZim

Its possible. I only re-wired the signal. I will look into the 5V supply. If I remember correctly, the TPS 5V supply shares/spliced to other sensor supply's so it will be a bit tricky to re-wire. I'll do some digging.

CCKen

Here's TPS test procedures if you need it.


Use a safety pin as a back probe.

DropTrooperZim

Update - I've since replaced the IAC(only cleaned it the first time) and replaced the TPS with an OEM Mopar TPS. Issue still present.

Ive since replaced the PCM with one from a pic-a-part lot. The issue continues. The replacement PCM may have the same issue as well but I doubt that is the case.

It is possible that the TCM is having issues? I plan to return the PCM and snag a TCM to see if that does anything.