AW4 won't shift up

[Garry '89/4.0]

Another victim of the pressure washer... so far I have disconnected and cleaned the main "double" connector on the firewall and the two connectors on the right rear side of the engine that head down towards the transmission. No joy yet.

 

Tomorrow I plan on doing the same with the connectors ON the tranny. I have also read that I may have toasted the TCM. If cleaning the remaining connectors doesn't work I reckon it's the TCM. If that's the case what "other" TCM's will work? (from what vehicles and year range) I don't have a huge choice of wreckers here, but there are 2 Cherokees that I know of.... greatly appreciate the help.

[deziped]

If you pressure washed your TPS you will have to dry it out somehow or replace it. But maybe its not the TPS so here some things you can check to narrow it down. Check fuse in Slot 13 of fuse panel to make sure 7.5 fuse is good. Check the in-line fuse at the TCM (Its on the back side of the fascia below the glove box). If its blown your TCM is not providing shift info to the AW4. If its OK then back probe the wires going from the TCM to the AW4 to check OHM's in Shift Solenoids. TCM must be unplugged, ignition off. Pin test cavity C16 (1st & 2nd gear Solenoid) for 11-15 ohms. Check 15 (3rd) for 11-15 ohms. If ohms are out of this range replace solenoids. Now plug the connector back to gether and with Key ON & Engine OFF check the TPS signal by: Probing D1 for DC vol of approx 5V. Probing D2 with closed throttle for approx 4.5V. Probing D2 at WO throttle for approx 0.5V. Probing D3 (TPS Ground) for approx 0.1V or less. Probing D16 for ign voltage of 12V. And finally with key OFF D14 should be battery V.

[alleydog]

A bad speed sensor can cause a no upshift problem. As i understand, it's just a magnetic switch that cycles on and off as the output shaft turns. Its at the leftrear of the tranny, and can be tested with an ohm meter.

[Garry '89/4.0]

Thanks for the info. team. Right now my garage is tied up and it's just too cold and rainy for these old bones to be crawling underneath so I did all I could up top (cleaning and blowing out connectors). I did manage to get the local transmission guru to hook up his Snap On 2500. It gave an error code something to the effect that there was no output/signal from the TPS. Thats as far as that went, he had others waiting. I'm sposed to keep calling him till I can get into his shop and he is a very busy fellow indeed. (I live in a small town that is a ferry ride to the big city).

 

When checking the fuse(s) I also disconnected the TCU and am able to shift manually.

At this point I'm thinking it would be faster and in the long run cheaper to just replace the suspect items, otherwise I'm a pedestrian for a week or more.

 

A TPS on-line runs $40 ~ $60 haven't checked the the price of the TCU but I would guess used is a good source? I have to get to the city this week to pick up my new (used) tailgate and dash panel and can *check the boneyards there for a TCU. What range of years and models of other Jeeps will work, just the XJ?...

 

Again, thanks for taking the time to reply.

[Garry '89/4.0]

Problem solved. The TPS tested bad. Found one at a wreckers, all is good now. Much Jeep Joy. For anyone with the same problem: To "bypass" the TCU so you can shift manually you do not have to disconnect the TCU, just pull the fuse. (no need to remove the lower dash panel). my thanks to posters