WJ transmission electric problems

Hey guys, my buddy has a 2002 Wj with the 4.7 that won't shift.
It takes off in third, and stays there, unless you pull the shifter down to 1st, then it's still taking off in 2nd. There is a CEL on, but no engine codes, so I went after Trans codes. I got a P1698, which is no signal from TCM.
I wasn't aware that these had a separate transmission controller other than the main computer for the engine. I know where the ECU is under the hood, and it has been replaced already with no change. I even took the valve body out and replaced the solenoid pack, and the fluid/filters, with no change, and the same code.
Does anybody have any ideas? Any clue where the TCM on that year model is?
2002 Wj
4.7 v8
Automatic
Lifted 4.5" on 33's with jk rubi wheels.
Looks pretty good for a mommy car on steroids, lol.

It's in limp mode.. Is there a fuse/relay for the TCU? TCU probably died. Not sure where it is. Maybe PM srmitchell, or Bryan C

Thanks. I checked every fuse labeled "Trans", and they were all good. There is a relay, but I don't know when it's supposed to click. I still haven't found a location for the TCM. When I google it, or images of it, I pretty much only find pictures of the PCM under the hood.

My buddy took it to the stealership, and was quoted $600 for a new tcu. I guess replacing everything is really profitable. Of anybody could tell me where the tcu is on an '02 Wj I could get one from he junkyard and install it for him...

The Transmission Control Module (TCM) is located in the engine compartment on the right (passenger) side and is mounted to the inner fender.

Hmmm we replaced that, but I thought that was the engine computer. Maybe the one we got from the junkyard had the same problem?

Btw, thank you very much for that picture.

Im not sure if you can just swap a TCU from one to another. They may have to be programed.

I had similar problems and it ended up being the speed sensor. I don't remember which one as the other one failed soon after. I got a jy tcu with no luck as well.
Hint: The input speed sensor is the same part as the output sensor. I couldn't find one or the other, there is no listing for it, they are indeed the same and inexpensive. Worth a shot.

poorboy87 said:

Im not sure if you can just swap a TCU from one to another. They may have to be programed.

Click to expand...

Mine didn't, but it is a 99. Still running the jy one for some reason. Have my original as a spare.

Many scanners won't read the tcu on the WJ. I had to find the right one. You may want to start there. Mine was working and it just wouldn't communicate with the scanner.

Thanks! I'll give that a shot!