Need HELP w/AW4 spinning out of overdrive

I have a 87 Cherokee with a overdrive issue. I have been searching with lots of info on transmission problems, but nothing on a transmission that spins out of overdrive going down the road. The transmission works fine except for this one problem.:dunno:
It will not do it cold works fine and after 10 miles or so in OD it will spin out like you threw it in neutral. After this you have to drop to 3rd and on the highway @ 45mph I'm taching 3500 rpm's.The local transmission shop made some adjustments, kick down cable,TPS checked good ,but solenoids checked bad, so we replaced all 3 and serviced transmission. The inside pan looked real good.They seem to think it's the overdrive clutches inside trans now. I still think it's electrical, because everything else about this transmission works great.Has anyone else had the same problem before? Please help!!!!
I can't keep spending money with no results. If it helps the Jeep has 200,000 miles on it with a rebuilt engine. I do not know history on trans. Thanks in advance.

I just went through hell with my AW4. My problem turned out to be a faulty valve body. You can probably find one at the salvage yard for cheap. I bought a rebuilt one for $125. But don't let the tranny shop run you up a bill for stuff you don't need. And I would avoid AAMCO at all costs.It can be hard to find someone who truly understands the AW4. Good Luck!

you could probably craigslist up another aw4 for like $100 and just toss it in and be done with it too...just one more option.

I can buy another used AW4 no problems, but if it's electrical or external then I'll have the same problem.I need to find someone that's had this problem before and solved it somehow. Could it be that the TPS checks o.k. at times and fails others?

Pull the fuse for the TCU. Its in the harness under the passenger side of the dash right up near the TCU. Then, shift manually with the shifter. You'll have 1st in (1-2), 3rd in (3) and 4th in (D) with no t/c lockup. If it drives and shifts okay like that, the problem is in the electronics.

It's possible that the rear output speed sensor is bad or the wiring to it is damaged. No signal from that sensor will make the TCU think you're not moving at it'll put the tranny in 1st. Usually, if that sensor is bad it shows up as not wanting to upshift out of 1st.

O.K I removed the fuse and seems to be fine. Do you think it could be the TCU ? I can drive the old heep now, so we're moving in the right direction.:clap:

If it's maually shifting with the TCU unplugged or its fuse pulled then it's about 95% likely it's an electrical problem. I would guess a bad sensor or shift solenoid before suspecting the TCU itself. I'd double check the resistance on the solenoids, measuring at the TCU connector itself. That'll check the wiring to the tranny as well as the solenoids. I believe they shuold be 11-15 ohms or there abouts.

I had the same problem, plus my TPS checked out OK when the motor was cold. Problem was I needed to check the TPS when it was hot! Turns out it had a dead spot only when it was warmed up.

It will drive ok with the fuse pulled(TCU disabled), because the TCU was receiving incorrect info.

Swapped the TPS and cured it right away.

Same deal w/ my TPS. It would test fine, w/ analog meter. I replaced it after a year of scratching my head and it's all good now.

O.K. I have the TPS ordered & plan to have installed asap.
I 'll let you know if problems solved. Thanks for all the help.
Power to the Jeep World!!:cheers:

SHESASASSY said:

O.K. I have the TPS ordered & plan to have installed asap.
I 'll let you know if problems solved. Thanks for all the help.
Power to the Jeep World!!:cheers:

Click to expand...

You do know that the TPS needs to be adjusted not just replaced don't you???

Yes, I have never calibrated one before so I have a appointment with local repair shop. Thanks for the input.

They are pretty easy to adjust and you'd be pretty close just marking where the old one is and put the new one in the same spot. You measure the supply voltage to the sensor (doesn't change when the move the throttle), and rotate the TPS until the sensor output reads 0.82 x the voltage you just measured.

You can get a decent meter for under $20 and do it yourself very easy. A multimeter is very helpful for any electrical work once you learn a few basics about using one. If you have a harbor freight near you, they have cheap ones with decent specs for $5, sometimes on sale for $2. I bought a dozen last time they were on sale and sold them $10 each on eBay. The Sears $20 multimeter is a good deal as well.

Well, now I know what I look like without hair,cause I've pulled all of it out! I had the TPS replaced and adjusted. The transmission still will slip out of overdrive to neutral,to keep moving you have to downshift to 3rd. If I pull the fuse in TCU then all seems O.K. I still don't think it's internal. I'm thinking about replacing the TCU. I'm still looking for a fix, anybody HELP.:dunno:

Try the brake switch too(at the pedal). Or test it anyway. It also controls the overdrive.

O.K. I wanted to update anyone that may have this problem in the future.
I did remove and clean the brake switch. I then installed the cleaned switch.The test drive proved a big change in the transmission shifts and so far after 2 days of driving I have not a moments trouble. If you have this problem please don't over look this switch. It's a little hard to get to, but had I known to check this first I could have saved a lot of money. Thanks to all that took the time to try & help.