Everything you ever wanted to know about the AW4

[klint96xj]

Well just to update, so far so good. The jeep passed emmisions, today with no problem at all. Thanks again Kastein for the help. I was on the edge of swapping in a 98+ transmission cause I couldn't figure it out. So you saved me a lot of work there!

But just to sum up everything I did, I used the 98+ wire harness and cut and spliced it to work with all of the 97 sensors. There wasn't much involved with that because the wires are all the same colors. But leave the plug for the ISS (Input Speed Sensor) alone and just zip tie it out of the way. The only reason for using the 98+ transmission harness is because the plug where it hooks in to the rest of the harness near the dipstick is different. Also used the new CPS (crank position sensor). Had to ground the one wire on the OSS (output shaft speed sensor).

Also replaced the 98+ TCM (Transmission Control Module) with the 97 TCM. (This required trimming a bit of plastic on the harness plug which doesn't hurt the plug in any way.)

Everything is working like it should on it now.

Hope this helps for anyone else wanting to try this.

 

[galatin]

WANT TO PUT AN aw4 IN place of the 999 in my 89wrangler so as to have OD where do I find the TCM in the donor car? And great thread.

 

[kastein]

96 down it is on the passenger side up under the bottom half of the dash, 97 up it is on the trans tunnel up and to the right of the gas pedal. I would stick with a roughly equivalent year, aim for a 91 up in any case as they have the 23 spline output shaft.

What year/engine wrangler?

 

[Milner]

Just read this entire thread!! Here's my problem.

Background: I have a 98 XJ that started as a 2wd. I used a donor AW4 from a 96. When I had the transmission rebuilt I had them use the 4wd output shaft and tailhousing from the 96 onto the 98.

Problem: I have now learned about the difference in the 96 OSS vs the 98. A 98 OSS will not fit in the 96 tailhousing. I need to some how get a 4 pulse pre rev output from the rear OSS. (I am getting a CEL p0720)

Options I can think of:
1: Find a junk 98 aw4 and swap the tailhousing enabling the proper OSS. (But is the tone ring/signal generator the same on the 96 output shaft as on the 98? I don't think they are.)
2: Swap to a 97 TCU
3: Pull my tailhousing and try to machine it to accept the 98 OSS.
4: In a dream world someone will know of a sensor with a 4 ppr output that will fit in my 96 tailhousing.

I am thinking option 2 is my best option? Thoughts?

 

[Milner]

I can now report that the 97 tcu/tcm does NOT always solve the issue of the differing OSS. I just completed the TCM swap and the 720 code still returns once I hit 3rd gear.
Off to find a 98 aw4 to steal the back half off of.
If I don't blow the jeep up first!!

 

[kastein]

You should be fine if you just swap a 98+ OSS rotor, OSS, and the 4wd housing over. The shaft is the same or close enough on all 23 spline 4wd AW4s that the rotor swaps over fine with some good lockring pliers.

The tone ring is not the same, but it does fit the same spot. Fortunately for you, because otherwise you would have to tear down the whole tranny to swap the output shaft again

Sorry to hear about the 97 TCU not solving the problem, that really sucks. Out of curiosity, did the donor have wiring in the harness for an ISS or no? I just realized the addition of the ISS may have occurred partway through 97 leading to your issue.

It is odd that you are getting the code for the OSS malfunction and no mention of the ISS or an incorrect ratio code. I think maybe you just have an OSS issue and the 97 TCU is fine? Have you checked the wiring and signal from the OSS?

 

[Milner]

It is odd that you are getting the code for the OSS malfunction and no mention of the ISS or an incorrect ratio code. I think maybe you just have an OSS issue and the 97 TCU is fine? Have you checked the wiring and signal from the OSS?

I have gone through the wiring, but have not checked the signal. Not sure how to check the signal.
The trans was gone from the 97 that I got the TCM from. So I am not sure what it had.
I am picking up a 98 4wd trans today. That way everything is as in should be. PITA, but no questions then.

THANKS

Edit: At this point I am wondering if my builder used the 98 tone ring on the shaft?

 

[kastein]

They might have. Pull the sensor out and peer through the hole while turning the output shaft in neutral, if you see 4 plastic lobes per rev it is a 98+ if you see 2 aluminum lobes it is 97-. There are two lobes for balance reasons but only one has a magnet in it.

 

[greaser]

very good info..well put, saves alot of :eyes:

 

[Milner]

Just for info
I just went to look at a "98" aw4 that was pulled.
As it turns out it had to be a 97. It had the new style ISS and the old style OSS with the 2 lobe tone wheel.
So as has been said the 97 TCM "should" solve my problem, but it doesn't.
Anyone have some explosives?

I would love to see which tone wheel is in mine! But it is in the Jeep with the tcase on....

 

[Milner]

Does the tcm use the VSS signal at all? Just thinking out loud. If the VSS is bad, could the code be due to a difference in the signals from the oss and vss?

 

[kastein]

Wait, now I'm confused. 97s don't have an ISS at all! At least, none I've ever seen. They just have the old style OSS.

So... I'm not sure what's going on with that.

edit: no, the TCU doesn't see the VSS signal at all. All it gets is the ISS (if equipped), OSS, NSS, brake lamp signal, and TPS. The VSS is after the transfer case (if any) and the TCU (and ECU) have no idea if the transfer case is in high or low range so they can't rely on the VSS reading to infer anything about the output speed of the transmission.

 

[Milner]

Wierd. The one I looked at today no doubt had the iss and old style oss. I could even see the 2 lobes of the tone wheel.....someone else had the same pos I do? To strange. Back to looking for a 98+ trans.

 

[kastein]

That is my only guess, yeah. They might have swapped the output to an old style one and put a 97 TCU in.

 

[Milner]

So I came found a 99 trans that was being parted out and got the tone ring, output housing and sensor.
Just pulled mine apart to swap it. I did have the 96 sensor and 96 tone ring. (but they did not work with the 97 tcm)
Went to put the 99 tone ring on and it is much thicker atleast 1/2". Therefore the snapring grove is covered and there is no grove to use to hold the 99 tone ring on. I did put the ring on and the output housing one to make sure the sensor hole lines up as it should. It does.
So the problem now is retaining the 99 tone ring on the shaft. As near as I can tell there is about 1/2" of space between the tone ring and the input of the tcase. I know it is hokey, but the only option I have (aside from changing the shaft) is to make a spacer to help retain the tone ring. I am thinking of still using the snap ring and then a 1/2" piece of heavy duty oil/gas resistant hose over the shaft. With the tcase in place, this would be an non rigid spacer to keep things where they belong.
Thoughts?

 

[kastein]

WTF?

That is odd. I don't remember that being an issue when I played around with those parts doing a trans for my 96, but then again that was five years ago and I might have just forgotten.

Yeah, there is no actual force on the rotor when it is in use - should be fine as long as the hose used is ATF-safe.

... now that I think about it, I may have had the opposite problem, since I was putting a 96 sensor/rotor into a 98+ trans. I don't remember what I did to make the rotor stay put, just that it slid on easily.

 

[B-17 guy]

Ok, forgive me. This is my first post here, I joined onto this forum because I found this thread while trying to figure out how to get an xj up and running.

I'm gonna do a very quick run down on what I got so you all can see where I am and what working with.
I currently have 2 xj's. The first is my green 96, 4.0 auto 4x4, 6" lift. Everything runs and works great but the body is badly rotted out.
I picked up a 98 recently that has a much better body but a blown engine. I figured it's perfect, rip out the 98's driveline and put my 96 all in.
Wrong. My 98 has an engine, computer and harness for a 00-01 which is coil on plug.
In the end I want to use as much of my 96 driveline in the 98 as possible because mine has been taken care of and I know it all works, can't say the same for the 98 that I bought from a young kid.
I figure use the 96 block, trans, tcase and axles. Put an 00-01 head on the block so I don't need to change harness or exhaust setup and be ok. Now I find out I can't use the 96 trans because the plugs are different and an added sensor.
So with the update from March 4 2013, says I can use a 97 tcu to get around the check engine light problem.
Does this mean that I can use the 96 trans in the 98?
Where is the tcu located exactly so I can change it? And where can I get one cheap?

Thank you in advance!

 

[B-17 guy]

Anyone?

 

[Milner]

UPDATE:
I have not been able to work on it for a month or so. Finally got it back together today and it WORKS!!
So for anyone that comes looking, here is the summary. I used a 98 2wd aw4 with a 96 donor for a output shaft and output/adapter housing. After coming here I discovered that was a problem. I tried the 97 TCU with 96 sensor. it did NOT work for me. It has for others.
I found a 99 output housing, sensor, and tone ring. BUT discovered that the thickness of the tone rings are different and my 96 shaft did not have the proper snap ring grove for the 98+ tone ring. So, I used a piece of hydralic hose just under a 1/2 think to hold the tone ring on. It sandwiches between the tone ring and the input snot of the tcase. Since it is not submerged and not under and load, it should not cause a problem and will stop the ring from moving.
Hope this helps someone else.

 

[Milner]

B-17
The 97 TCU has worked for some, I am not one of them! I do have a 97 TCU to sell if you want to try it.