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AW4 only goes forward

ktwalker01 said:
Possibly when you drained out the old fluid you might have done some wrong to it.. I am not an expert with the AW4 but I know with most autos when it is older and poorly taken care of when you go ahead and just drain out all the old fluid and replace it with new you sometimes have a bigger problem on your hands because some of that dirt in the old oil is keeping your tranny in check oddly enough.
Click to expand...
x2. Your reverse clutch pack might just be garbage and the gunk in the old fluid was the only thing left holding it together.
 
I don't understand how just a fluid change alone would disturb clutch packs... if there was buildup of any kind on the clutch pack, the fluid change should not disturb that. ???
 
lawsoncl said:
True, but with the TCU unplugged you have no solenoids engaged and you still get reverse.
Click to expand...

OK, got it, but now I am curious why it activates solenoid #1 when it doesn't need to in reverse. I see in the FSM you are right, reverse not working is either a linkage, or valve body or clutch pack problem.

Sounds like he may have internal problems, at least in the valve body linkage if not the tranny clutches themselves.
 
T fluid and clutch packs are strange beasts. Burnt fluid, particles from wear, or the wrong fluid, or even just clean fluid in a dirty transmission can make it seem to puke. Might try some Trans X, and a few fluid changes to see if it cleans up. You never get more than about a 1/3 out each time you drain it. Most of the fluid stays in the TC. It has no drain.
 
Ecomike said:
lawsoncl,

how does the TCM gets its signal as to which gear has been selected? I am guessing the NSS, if that is true shouldn't he be working on it too, or does the TCU not care, and only looks at the VSS? I am thinking for some reason the NSS in Park, Reverse and neutral talks to the TCU, but I have not looked it up.
Click to expand...

I have disconnected several NSS and jumped pins to make them start and never had any shifting issues leaving the harness disconnected. I have done this on 87, 89, 91, 94, and 95 models. Like mentioned it may be diffrent on later models, but I have never had any issues with any of mine.
All were 4.0/aw4 combos...IIRC all 231 t-cases.

The only adverse effects that I had were a lack of backup lights.
 
I've been going over the hydraulic application charts for '97 (Sorry, Chrysler doesn't have any service info for earlier years on their tech website). I believe however that the AW4 hasn't changed, ever. The only thing I could think of is a worn 1st/Reverse Brake is blown out somehow. It's only applied in reverse, and manual low (1-2). It's a clutch pack that locks the rear planetary carrier to the transmission case.
 
docboy209 said:
I've been going over the hydraulic application charts for '97 (Sorry, Chrysler doesn't have any service info for earlier years on their tech website). I believe however that the AW4 hasn't changed, ever. The only thing I could think of is a worn 1st/Reverse Brake is blown out somehow. It's only applied in reverse, and manual low (1-2). It's a clutch pack that locks the rear planetary carrier to the transmission case.
Click to expand...

Don't forget the valve body, something could be stuck in it causing the loss of clutch operation.
 
This thread is bout my 89 xj my friend started

I decided to scrap the old trans and probably the np242 t-case as well, Im done screwing with it, Its leaking again now. I have a 98 aw4 23 spline so ill put a 231 t-case on it but I know the wiring is different I think? something with the speed sensor or something? what do I need to do to make it work on my 89?
 
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docboy209 said:
I've been going over the hydraulic application charts for '97 (Sorry, Chrysler doesn't have any service info for earlier years on their tech website). I believe however that the AW4 hasn't changed, ever. The only thing I could think of is a worn 1st/Reverse Brake is blown out somehow. It's only applied in reverse, and manual low (1-2). It's a clutch pack that locks the rear planetary carrier to the transmission case.
Click to expand...

A few things definitely changed along the way, although I'm not sure how significant they were. The output shaft spline count and the 4th gear ratio changed mid 1990? Front speed sensor was added in 98 (I think). I believe the valve body also had some changes as the solenoids are slightly different. The solenoids fit, but the guy I sold a set of 89 solenoids to said he had problems installing them in a 98. The connectors came off the solenoids on the opposite sites and he had to connect the wires before installing them as there was no room to get the connectors on after.
 
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89mudder said:
This thread is bout my 89 xj my friend started

I decided to scrap the old trans and probably the np242 t-case as well, Im done screwing with it, Its leaking again now. I have a 98 aw4 23 spline so ill put a 231 t-case on it but I know the wiring is different I think? something with the speed sensor or something? what do I need to do to make it work on my 89?
Click to expand...

Aside from the spline count issue, the rear output speed sensor changed.
http://www.naxja.org/forum/showpost.php?p=243739279
http://www.naxja.org/forum/showthread.php?t=972069
http://www.naxja.org/forum/showthread.php?t=959184
 
no I have the working 98 aw4 and i Just need the 231 t case and to figure out what wiring issues I need to fix to make it work in the 89 xj truck.
 
I had the same problem as XJ atticus but mine was caused by driving the jeep around with little to no fluid in the trans (tranny line got cut and dumped most of the fluid on the ground while on the trail). I managed to limp it home and put some more fluid in it but it didnt fix the problem. Im thinking the tranny is toast but if there is a way to salvage it, that would be great!
 
Eric85 said:
I had the same problem as XJ atticus but mine was caused by driving the jeep around with little to no fluid in the trans (tranny line got cut and dumped most of the fluid on the ground while on the trail). I managed to limp it home and put some more fluid in it but it didnt fix the problem. Im thinking the tranny is toast but if there is a way to salvage it, that would be great!
Click to expand...

What exactly is the problem? A good flush and refill with Dexron III might help, and many folks here have recommended some of the Trans-RX type of stuff to help un-gummup the tranny as well. But if its really burnt up clutches then it may be beyond hope and a decent used tranny would be worth considering.
 
The problem is, the jeep moves forward in every gear except for park. Even while in park the engine sounds like it is under load. I assume its time for a new one, which is no big deal as i never drive that jeep.
 
so it took a little brass monkey and elbow grease but I got the 98 aw4 and np231 in and it seems to work great now, all gears and reverse too!!!
 
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