Hoping I can get some ideas before Monday rolls around. Have a 90 XJ 4.0 automatic that suddenly stopped shifting. Was driving and everything was fine then my RPM’s shot up but it wouldn’t shift. Everything else is working though (park, reverse, etc). I can stop at a light and give it gas and it’ll go, just not over 2,000 rpm’s. Kinda just limps along. Engine temp doesn’t show it’s overheated so unsure where to start looking. Thanks for any help!

 

1st I would check all power and grounds then unplug the computers engine and trans making sure that all connections are clean . and maybe check the the connection at the trans also .

 

Go to cruiser54's tips on all things Renix Jeeps, link below Then bookmark it for future reference.

WithIn this website, you will find a section related to verifying your "throttle position sensor". Test yours as the TPS is directly involved with shifting characteristics of your AW4 transmission.

https://cruiser54.com/

Also verify fluid condition and level, and check to be sure that your throttle valve cable is in proper adjustment.

 

Do Tips 1 and 10 at www.cruiser54.com first, after checking fluid level and condition.

Check the fuse for the trans control unit.

What happens if you pull the lever down to 1-2 and accelerate from a stop?

 

Same thing, it still won’t shift. Fluid was good, so I’ll check out the other tips. Thanks for the link

 

Not upshifting from first is more likely going to be a bad throttle position sensor, bad #2 shift solenoid, or damaged wiring to the output speed sensor.

 

So, for clarification, with the lever in D, it never shifts out of first?

 

Correct. It revs up like it wants to but never actually shifts. Going to see if I can find somebody to test the TPS today

 

Thanks! Trying to find somebody who could test the TPS and I’ll see if I can’t do the others. What do I need to check the solenoid and wiring?

 

For the solenoids, you can test their resistance at the connector under the hood up near the firewall on the passenger side. The diagram below has the right pinout, but is for a later model with different wire colors (they're close, like violet instead of violet with a white stripe). The C14,C15,C16 are the pinouts on the connector on the trans computer itself, which is located under the dash below the glove box. The solenoids should be 11-15 ohms. S2 would be the suspect if it's not shifting into 2nd gear. Only S1 is on for 1st, both S1 and S2 are on for second, just S2 for 3rd, and neither for 4th. S3 is the torque converter lockup. I'm betting TPS though, especially if you got it wet.

 

Thanks for the diagram, that helps a lot. Didn’t get anything wet, it just quit while I was driving down a dirt road. Got a couple leads to hopefully check today, thanks again

 

So update, the whole tranny was done for and the tranny filter was plugged. Going to have to put a new one in. Thanks for all the leads everyone!