Hey everyone ! I'm new to the forum but I'm already amazed how much usefull information this site has!

I have a a question for u guys and I'm sure u can help me out!
I have a 1990 Cherokee with a automatic tranny and when I first get in it and drive it it shifts nice and smooth like nothing is wrong then after around 15 or 20 minutes if I come to a complete stop and then drive off again it won't shift out of first gear even if I try to shift it manually! It continues to not shift until I park it and let if fully cool down then its back to normal until I drive it for the same period of time ! I bought a tranny gasket and filter kit but was thinking I should wait to install it until I can get some information just incase I have to replace a solinoid or something inside the tranny that way I can do it all at once !
Please let me know what u guys think or if anyone has had the same problem !

 

1. Be sure fluid is at the correct level, fresh and clean or replace the filter (it's basically a screen) if you don't know the history of fluid changes and maintenance. Use Dex/Merc III compatible fluid for the AW4.

2. Test your THROTTLE POSITION SENSOR. And also be sure it is adjusted. A bad TPS is the cause of many shifting issues on the AW4, especially on 87-90. The tranny relies on that TPS signal more than anyone knows. More on the TPS below.

3. Solenoid is a possibility, but I'd concentrate on the above first. Then start testing things like solenoids and the TCU.
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RENIX TPS
(Thanks to Joe Peters from NAXJA for this information)

MANUAL TRANSMISSION:

RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector. Wire "A" is positive. Wire "D" is ground. Remove the three-wire connector from the TPS. Key ON, measure voltage from "A" positive to "D" ground. Note the voltage reading--this is your REFERENCE voltage. Now, reconnect the three-wire connector to the TPS. Key ON, back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. Adjust the TPS until you have achieved this percentage, if you can't achieve the correct output voltage replace the TPS and start over.

AUTOMATIC TRANSMISSION:

RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a four-wire connector. For the automatic transmission equipped vehicles the four-wire connector provides data to the TCU. Disconnect the four-wire connector. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Now, reconnect the four-wire connector to the TPS. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. Adjust the TPS until you have achieved this percentage, if you can't replace the TPS and start over.

So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire connector side of the TPS. If you have ENGINE issues check the three-wire connector side of the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.

 

When you have the pan off to change the filter test the solenoids with a VOM.

 

Try this, remove the fuse for the trans control unit OR unplug the trans control unit, and try shifting manually. 1-2 should get you 1st, 3 should get you 3rd and D should get you OD, but it won't shift electronically. If it works consistently in manual mode, then its an electrical problem.

At 4500 rpm it should shift from 1st into 2nd from pressure whether the TCU is working or not.

You can test the solenoids through the female 7 pin connector by the trans dipstick.

PM me you email address and I'll send the AW4 trans troublehsooting manual as an attachment. It is very detailed.

 

A dirty screen/filter will give you the results you have also. After driving some the screen completely clogs and after resting the crud falls off back into the pan .
then you go again and repick up the crud
Take pan off and see what U see.

 

Thanks guys! I'm going to take everyones advice and see if I can get this thing figured out . I'll post my results within the next few days as soon as I can get some time to work on it !

 

Ok guys so last night I drove my jeep and as usual after about 20 min of driving it wouldn't shift out of first gear automatically or manually ! So I disconnected the tcu and I was able to shift manually . I tested the tps and came up with .840 . Is that really far enough out of adjustment to cause shifting problems

 

If you were able to shift manually, the problem is most likely electronic rather than mechanical. Items in play other than the TCU is the throttle position sensor, vehicle speed sensor, and brake pedal switch. The brake pedal switch disengages lockup of the torque converter. The other electronic items are the S1 and S2 shift solenoids. If S1 isn't working it won't select 1st when put into D or 3.

The TPS with 3 leads should have a 5v input lead, a ground lead, and an output lead. My ouput ('96) was .76v with the throttle closed and 3.7x with the throttle wide open. It needs to be a smooth increase from closed to open with no flat spots, so an analog meter will better show the result.

 

Ok so I pulled the pan and every thing was clean and looked normal ! I changed the filter and fluid and it still didn't fix the problem ! I also tested the tps and adjusted it my first results were .840 and I read that anywhere between .825 and .835 was acceptable with .830 being optimal after I adjusted the tps I came up with .828 . I took it for a test drive and still after about 20 min of driving the problem occurred again! I tested the tps again as soon as it happened and couldn't come up with any results ! The numbers were fluctuating and were also coming up with negative numbers! Does any one know what would cause this ? A bad tps or ecu or tcu ?

 

Have you tried another TCU? You don't mention what year.

 

Im in the same boat as you! Im gonna tear into the wiring this weekend and ill let you know what I come up with. Im sure between two of us and the support of CF we can figure something out. Good luck

 

Got a Buddy with an 89 that was doing the same thing... Curious to see the end result! Sure it'll be something Diff between the 3 of them though!

 

Sounds just like when I had a bad Throttle Position Sensor in my 96. Would work OK when engine was still in warm-up cycle, but as soon as it was hot it wouldn't shift out of 1st gear no matter what. It seemed to test OK with an analog Multimeter as well. I had ruled everything else out so I just replaced it and bam! back to normal with all gears shifting fine in the AW4 auto. Make sure to order the one from the Jeep dealer, it's worth the extra $$$ I got a faulty one (OMIX) from a website and had to order a dealer one. GRRR. Plus everyone says they last way longer too.

 

The reason I asked what year is because the RENIX TPS is adjustable, but the later 3 lead are not. There is no point in replacing a RENIX TPS if you don't know how to adjust it.

 

finally!!! Got the problem solved ! Ended up being the tps installed and adjusted the new one last night and drove it for about a hour and a half with no issues ! Hope this helps the rest of u guys with the same problem !