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aw4 rebuild

P

pb_beaker

NAXJA Forum User
Location
in a van down by the river
where can i get an exploded view of my 89 4.0 auto, aw4 tranny? It needs some work. It works great in reverse but in drive it moves very slow even with alot of skinny pedel. Any suggestions?
 
Does it take off properly with the shifter in (1-2)? Just wondering if it's staying in 4th in (D), which would normally point to no power to the TCU.
 
Could be a bad TPS on the TCU side of the TPS. Lots of stories here on that problem in the RenX files thread. Mine was upshifting at like 1200 rpm and never had any power, it was a bad tps.

Lawsoncl is one of the top AW4 experts here, so follow his questions closely. The AW4 is electronically controlled by a computer, called the TCU. It operates 3 electric solenoids in the transmission that together (TCU, TPS and slenoids) control shifting points, but it will operate in 1-2, 3 shifting manually with out the TCU. So it is possible the test the transmission hardware only with the TCU disconnetced or powered down.
 
sorry for the late post but here it is. Put it in 1-2 gear and works awsome, great power and quick accel. 3rd is fine but when i put it in drive its like it is starting in 4th. Not familiar with this tranny so where is and how do i test and adjust the TCU?
 
Small silver box apx 5" x 3" x 1" mounted behind the lower dash, about knee high on the passenger side. There is an in line fuse near it that may be blown.

Also, you need to test the TCU side of the TPS sensor to see if it has gone bad. Check the fuse and the TPS first.

PM me your email address.
 
read up a little on the TPS and will adjust that when i get home and also check the TCU. I had some issues with my dodge diesel a few weeks ago and it ended up being the kick down cable, does this vehicle have anything like that?
 
Unplug the transmission control unit and shift manually.

1-2 will give you 1st gear, 3 will give you third gear, and D will give you 4th. Sure, you won't get second gear, but it'll tell you if your transmission is working or not, and if you only have an electronic problem or not.
 
Yes there is a kick down cable attached to the throttle body area, but the extreemes of the settings on it are not wide enough to cause to your problems, the electronics are. TCU Fuse, power to the TPS and bad TPS sensors are common AW4 operation problem sources on the older jeeps.

There are several threads and pictures here on the kick down cable and how to set it, takes about 30 seconds to do, but unless someone messed with it and unset it (pulled the throttle body?) it does not unset itself.
 
well... am i missing something?
jeep001.jpg


the TPS doesnt seem to be the problem.
 
pb_beaker said:
well... am i missing something?
Click to expand...
Um, yes. The piece of harness hanging down (has the fuse hanging out) is suppose to plug into the trans computer, which appears to be missing. The connector looks a little mangled as well. The trans computer attaches to the lower trim piece which also appears to be missing.

The TCU looks like this one on ebay http://tinyurl.com/5p6gqq. When you're looking for a replacement, believe 87-90 are all the same and the connector should be grey (not green or red for later years and trannys).

For now, you should be able to shift manually with the shifter, or lookup awshifting.com for a way to do a manual electronic shifter.
 
Last edited:
Dude! Your missing the passenger door too! LOL.

Depending on your plans for the jeep either a JY TCU (they are common and cheap) or the manual electric switchs option is a good choice. TCU should be on Ebay somewhere too.
 
pb_beaker said:
sorry for the late post but here it is. Put it in 1-2 gear and works awsome, great power and quick accel. 3rd is fine but when i put it in drive its like it is starting in 4th. Not familiar with this tranny so where is and how do i test and adjust the TCU?
Click to expand...
Your trans just might be OK ....like was posted here...... your TCU is missing so.....................
Blaine B. said:
Unplug the transmission control unit and shift manually.

1-2 will give you 1st gear, 3 will give you third gear, and D will give you 4th. Sure, you won't get second gear, but it'll tell you if your transmission is working or not, and if you only have an electronic problem or not.
Click to expand...
That's how I found out mine was OK (the trans that is)..................
 
Ecomike said:
Dude! Your missing the passenger door too! LOL.

Depending on your plans for the jeep either a JY TCU (they are common and cheap) or the manual electric switchs option is a good choice. TCU should be on Ebay somewhere too.
Click to expand...

Yeah i have not put on the door, heres the driver door and what it will look like.
IMG_0606.jpg


IMG_0603.jpg
 
i baught the jeep from a co-worker for $500 and it was all tore up. Have put a lot of time into. The doors were made by his neighbor cause he was goint to fix eveything, but after it sat outside for over a year and a half he sold me evrythin. I really like the doors also, i dont know if you can tell but the kind of go out then come back in. Gives you alot more room.
 
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