Xj Transmission Problem

I just purchased a 90 jeep cherokee. It had a bad engine and replaced it with a 95 4.0 liter. It started up great, but when I test drove it, it acts like its stuck in 1st gear. I have checked and re-checked all of my wireing, every thing is pluged in. I have checked the fluid, I have re-adjusted the trottle cable. Nothing has helped. I am running out of ideas. Can anyone help, please.

I tried unpluging the TCU, and when I did that and test drove it, its now stuck in a higher gear. So I know the tranny will go into another gear, but can't figure out why it won't shift.

Before you R&R the engine, did you notice anything wrong with the tranny? Make sure that you have both harnesses(p/s firewall) connected. If you select 1st gear will it work, if so, driving it, can you manually up shift the tranny by way of the shifter?

When I first bought I could only drive in the trailer because the engine had a really bad knock, so I did not get to test drive it. The gentlemen I bought it from was very honest, told me every thing that was wrong with it. He said it drove fine before he blow a rod.

The tranny connecter are all plugged in. I have taken apart the NSS. It was very clean, but I cleaned it again.

And no, it will not shift manually. It stays in 1st. gear. I did try driving down the road, and unpluged the TCU, and it shifted into a higher gear. After the TCU is unplugged its stuck in that higher gear, until its plugged back in. So I have no idea if I have a electrical or mechanical problem. Thank you very much for your reply.

OK, I have consulted with the ATSG Manuel on this tranny. Try this, with the engine running, disconnect TCU, it should back up in reverse, neutral, provide 1 gear with shifter in 1-2 position, operate only in 3rd gear in 3 position, operate in 4th gear (overdrive) only. I know you said it would not work at all and went right into 4th gear once you unplugged the tcu. (This would happen if you were in, or went into D first. Doing this you have all but eliminated the electrical portion of the tranny, and have isolated it to mechanical and hydraulic pressure. Unfortunatly this is the more expensive portion. THe rest of the testing it lists requires pressure guages, not something you can get readily at parts store. Recommend pricing a rebuild, but double check everything, like linkage and such. I have a 89 AW-4 here if you are interested.

Thank you very much for your reply, gtmud. I have spent several hours researching this problem, and a few have said stuff about the TPS. So I decide to check it out. It wasn't sending out a signal, so i went to the local part store, and for under fifty bucks I bought one. Got home plugged it in, and some way, some how, it has fixed my problem. Can you believe it trottle positioning senser, it fix it. Thanks again for your help. Now its time to modify, so I will be back for some help soon.

Thank you very much for your reply, gtmud. I have spent several hours researching this problem, and a few have said stuff about the TPS. So I decide to check it out. It wasn't sending out a signal, so i went to the local part store, and for under fifty bucks I bought one. Got home plugged it in, and some way, some how, it has fixed my problem. Can you believe it trottle positioning senser, it fix it. Thanks again for your help. Now its time to modify, so I will be back for some help soon.
Thank you for taking the trouble to let us know the remedy.

I would not have thought of the TPS being the source of the trouble, so good for you! :wink:

COOL!! Glad that you were able to fix the issue, much better than another tranny. If you are looking for upgrades, I recommend getting a set of #19 ford 5.0 injectors and header. I have this on my 89, and boy does she run!! Even at 154K, also get the coolant system switched over to the open type if not already done.