Medic08

So here is a question. Well really just me seeing if I am thinking right. I bought a 91 xj limited. When you put it into drive it does nothing. It will however shift fine manually. Am I right in thinking it is probably the TCM? Maybe possible the TPS? Let me know what you think. Thanks for your time.

Gorillaxj

IF it won't shift on its own, but will shift manually it is the control unit, unless its not seeing what it should in order to operate. but sounds like a TCM to me.

excess650

Research the TPS to see if yours is outputting correct voltages.

There may be an inline fuse in the wiring harness for your TCU. If that fuse is blown, it will only shift manually. There may also be fuses in your fuse box(es) depending upon your model year.

The speed sensor on the rear of the trans may also be the culprit.

My '96 has a similar issue that I've not yet resolved.

If and when you discover the problem, please post your findings.

Medic08

So I found the problem. The fuse under the hood keeps blowing. Like as soon as I put one in and turn the key. Any idea what may be the cause of this? Thanks for any ideas.

Gorillaxj

what is the fuse for?

Medic08

It is labeled transmission. I assume it is the one for power to the TCM.

Gorillaxj

based off this wiring diagram for a 1991 Cherokee 4.0L i would replace the TCM. or it could have a short to ground. if you unplug the TCM and place a new fuse in the spot and it doesn't blow then it should defiantly be the TCM...IF it does blow then its a short to ground in the harness. the fuse is the only feed to the TCM(from the diagrams i am seeing) I am thinking that the TCM has an internal short which is blowing your fuse. I would run to a JY and get a different one and swap it out.

Medic08

Thanks a lot. I am out of fuses and had a different TCM but I forget which one I had plugged in at the time. lol I may have plugged the old one back in by the time I found a few fuses to try. I will try to sort it out tomorrow.