Error P0122 - 1998 Jeep Cherokee
Over the last several days, perhaps a week or so, I noticed a brief hesitation. I was concerned that the adapter between the OEM wiring and the high performance coil was becoming lose again.
Today on the way to work the hesitation began to act like more of a miss. Idle and cruise seemed fine, it was only when I was moving the throttle that I noticed a problem. More throttle didn't make things any better. It would come and go.
When I got to work and put the transmission in park, I noticed the engine RPM sounded higher than normal. I looked and it was about 1200 to 1300 RPM. This clued me to the problem, it was the Throttle Position Sensor (TPS), or if not the hesitation problem at least I felt the TPS had a problem. I had replaced the TPS about four years ago, after having the same high rev issue.
After getting back home for the day I set about installing my Rough Country tie rod, and completing the installation of the Rough Country quick disconnects. Since a CHECK ENGINE light had come on during the trip home I grabbed my laptop and my OBD II scanner.
I got the codes and sure enough one had to do with the TPS, low voltage. Confident that this was just an issue with the TPS I left to go to the auto parts place.
I got a Borg Warner with lifetime warranty. I guess they don't know how long I'm keeping this thing! :rotfl2: I came home and quickly replaced it. Two star head screws out, replace the TPS and two screws back in. Replaced the harness connector and jumped in for a test drive.
NO CHANGE!
Tired from the installation and the heat of summer, I came in to rest and worry about my poor Jeep. I started digging on the Internet. I found that low voltage from the TPS usually means a short in the wire going from the TPS to the ECU. It could also be a bad ECU, of course it could be a bad TPS, but I had already replaced that.
Dig dig dig. I read about the Grand Cherokee problem where the harness rubs on a bolt from the valve cover and causes a short. Then I read about a Cherokee XJ owner that found the problem after reading about the Grand issue, but his harness was rubbing on the back of the fuel rail.
I checked mine, and you could clearly see that a small hole had been rubbed into the plastic covering around the 50+ wires in the bundle. I tried looking at each wire by moving them around with a screwdriver but I couldn't see any exposed copper wire.
I took a couple of tie wraps and pulled the harness up and off the back of the fuel rail. A test drive confirmed that the hesitation, transmission failure to shift correctly to 2nd gear, and the check engine light stayed off.
You never know for sure about these things. It may come back and I'll have to trace it down a little further. You might want to save yourself a future headache and suspend the harness now. This appears to be an issue on 1998 and 1999 Jeep Cherokees. Maybe more years, but at lest on these two years.
http://xjtalk.com/images/special/jeepp0122error.jpg
Re: Error P0122 - 1998 Jeep Cherokee
Re: Error P0122 - 1998 Jeep Cherokee
Looks like yo need to armor that up.
