[Silver04TJ]

I have an 04 Wrangler. My check engine light started coming on and I was getting the following error codes:

P121
P122
P123

The motor would jump occasionally as if the gas would shut off all of a sudden then come back on instantly. When pulling out it would act like it did not want to go then all of a sudden take off. I took it to a mechanic and he said there was a ground wire in the steering column that would corrode if you left the top off and moisture got to it. He ran a new ground wire and cleared the error. About 2 weeks later it did it again. Now off and on the the check engine light will come on and it will start jumping and drag when pulling out. Anyone have this happen? Know if that is the problem or if it is something else?

Thanks.

[RDNZL]

121 - TPS and MAP sensor disagree with each other
122 - TPS voltage low
123 - TPS voltage high

I think that your Throttle Position Sensor is bad. These are not water proof, and can corrode. When mine went bad in my 1996 Cherokee, I got the same exact problem that you did. Exactly. This is real easy to change too, Autozone i think is about $47. Two t20 screws.

Thing is that as your throttle moves through its range of motion, the TPS gets to an area of corrosion doesn't make good contact and it thinks that you just slammed the throttle shut instantly. Then it moves past that area and it thinks that you just went from full closed throttle to 3/4 with nothing in between. This is why you get the severe on/off of the gas delivery.

Never go to that mechanic again. He is either stupid, or he thinks that you are.
Intermittent problems are hard to diagnose, and sometimes mechanics would rather replace something and get paid, not caring if the problem is actually fixed. Mechanics are like any other group of people, you will find saints and you will find some evil bastards, and everything in between. Find a good shop and always go back. I only go to one shop in my area, and I always go back and talk to the mechanic after I pay and TIP the mechanic. I have never had to go back to this shop a second time for the same problem. I don't get my van/car/Jeep back as quickly as some shops.... but that is because this place is really busy with long term repeat customers.

[Silver04TJ]

That sounds like it is more than likely the problem. I'll give it a try and see how it goes. Thanks for the help.!

[Silver04TJ]

Where is the TPS located? Is there anything special I have to do when replacing it or is it just a "pull the old one and replace with the new one" kind of procedure?

[RDNZL]

It's on the throtle body, on the same arm that hold the butterfly valve. The throttle body is on top of the intake manifold. Follow the large back plastic tube from the air box, it connects to the top of the throttle body. TPS is held on by 2 T20 screws I think.



In this picture The TPS is the black part on the right (which when you stand at your grill and look at your throttle body, it will be in back... at least it is on my 1997 Wrangler I6 4.0). In this picture in the back is the Idle Air Control Valve ( IACV ). In the front you can see a tube with screw holes on either side, that is where the Manifold Absolute Pressure ( MAP ) sensor will be on yours.

On my Cherokee I just unplugged it and replaced it. You should remove your throttle body and clean it at the same time. It is held on by 4 10MM bolts I think. Just make sure that you get a Throttle Body base gasket and IACV housing base gasket (Autozone stocked the throttle body base gasket, but not the IACV housing base gasket, so I just bought a roll of cut your own gasket, remove the old one carefully and it isn't that hard. Never reuse gaskets, yours will be smashed and not seal well and can cause leaks. Make sure that you clean the gasket surfaces without scratching them. Remove the TPS, IACV, MAP sensor and IACV housing (which might be held on by security torx). Don't try to move the plunger on the IACV when you take it out of the housing. The throttle linkages just pop off. Clean it all up with carb and choke cleaner, small toothbrush, q-tips and pipe cleaners. Remove the butterfly and you can clean it out better, get the edges of the butterfly.
Disconnect the battery before removing the throttle body, and hook it back up after wards, turn the key to on, but do not start, turn the headlights on for 30 seconds. Drive for 10 miles. That should let your engine relearn the clean throttle body.

Your throttle body might not look very dirty, but if it hasn't been done in a while, or ever, I bet you can feel a difference afterwards. And it might help a little on MPG. Anything that cheap that can help on MPG right now can't be a bad thing.

BTW, go to Autozone for the TPS, they chage about $47, the dealership I went to wanted $102!

[Silver04TJ]

You have been more than helpful!!!!!!!!!