jeepacabra

I'm having problems with my AW4 tranny. When pulling out transmission shifts through gears fine but will not go into overdrive and sometimes if you put the gas to the floor it's getting to much gas and not enough power from the trans like it's in to high of a gear. Shifts manually okay except for overdrive. This is a transplanted motor & trans. Would the transmission control module maybe out of a older '90 Cherokee not have same data going to the computer that it needs? Should I try & match a '95 computer & TCM out of the same Jeep? When trying to drive at speed (45-50) trans will overheat like it's working to hard and I cannot get more speed because it will not shift into overdrive. Shift cable is okay.

FourWinds

I've got an '88 Cherokee with an AW4 and have been having problems with it shifting. I finally isolated it to be the TCU that's bad in mine so I've got it unhooked and I shift manually, which is a pain but it works (basically). I've done a fair bit of research/reading about 'Jeep' AW4s/TCUs and related issues and as I seen to remember, pre '95s had a separate TCU/TCM.

I believe it was '95 is when they eliminated the separate TCU/TCM and incorporated it into the one ecu/pcm. If a separate TCU was transplanted along with the motor/tranny when it maybe shouldn't have been, that might be part of the problem you're having. My '88 AW4 has 3 solenoids in it with #3 operating torque converter lock-up/OD so a bad #3 might be something for you to consider.

There's probably a fella or two on here that knows better than me.

jeepacabra

Thanks for the response. I've narrowed down one problem. I unplugged the TCU and ran 12v to each solenoid, the #3 overdrive solenoid does not click. So now it's time to tear it down and try to replace the solenoid and see where that gets me.

FourWinds

Good luck, man... I hope it fixes your problem.