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Discussion Starter · #1 ·
Just picked up a 98 AW-4 to put into my 90 XJ.

The gentlemen I bought it from alluded to the fact that I would need to do some wiring on this to make the swap work.

Any pointers on this? ...........and yes, I searched!:flipoff2:

Thanks,
Jay
 

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It'll never work, impossible! :flipoff2: fawker, Judd
 

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Discussion Starter · #6 ·
I looked at the TJ swap, but it was for retrofitting an automatic into a jeep that had a manual......

I realize that the 98 has the 23 spline.....that is why I got it: so it would mate to the D300 I bought. (Plus it has 110K less miles than mine!)

My question is: Are there any OTHER differences between the 90 AW-4 and the 98 version that would prevent this from being a plug and play swap?

Thanks,
Jay
 

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jlake1 said:
My question is: Are there any OTHER differences between the 90 AW-4 and the 98 version that would prevent this from being a plug and play swap?
If you use the TCU that matches the '98 version it *might* work. That is assuming the signals that come from your '90 PCM are the correct voltage to work with the '98 TCU.

Another option might be to keep your '90 TCU and salvage as much of the electronics as you can from your tranny to swap over to the new tranny. :confused:
 

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Discussion Starter · #8 ·
I do have the 98 TCU. What year did they change the signal voltages?
 

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I am no expert here, But I think if possible I would look into keeping all of the old electronics off of the 90 model. The 98 is going to have all of the ODB2 garbage. I think it would be best to avoid that 98 TCU if at all possible.

I plan on doing this swap on my 89 XJ when I put in the stroker. I have not even given any thought to how this will all work, yet. But I will watch this thread to see how you do.

-Scott
 

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jlake1 said:
I do have the 98 TCU. What year did they change the signal voltages?
I really don't know what the differences are. I believe that OBDII started in '98 so that may be when they changed voltages.
 

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jlake1 said:
I do have the 98 TCU. What year did they change the signal voltages?

They never changed.

The AW4 feed voltages are the same, the connectors and the output spline count changed.

Splice in the 90' connectors.

The only other change is a slight difference in the OD-4th gear ratio (0.70:1 to 0.72:1., or the other way around).

BTW, I run a 97 AW4 in my 88 XJ (same style of swap).

Happy Trails!
 

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Ed A. Stevens said:



They never changed.

The AW4 feed voltages are the same, the connectors and the output spline count changed.

Splice in the 90' connectors.

The only other change is a slight difference in the OD-4th gear ratio (0.70:1 to 0.72:1., or the other way around).

BTW, I run a 97 AW4 in my 88 XJ (same style of swap).

Happy Trails!
So what your saying is you can use any AW-4 as long as you have a TCU to match your engine and the correct input gear for the T-case. You just have to swap the connectors on the tranny to match the existing harness?
 

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LJRXJ said:
I believe 1990 XJ has 21 spline while '98 AW-4 is 23 spline.
They switched spline counts in '90 mid year. You can find some '90 AW4s with 21 or 23 spline...
 

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I'm pretty sure he realizes the spline count since he got the tranny so it would mate up to the 300. To answer your question....Cut the 98 TCU connector off and splice it onto the 90 connector. That way no OBD2 crap and you keep the 90 electronics. The rest is just the standard transmission install stuff. Good luck.
 

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Just pointing out some FYI on the spline count change for anyone that reads this post and is thinking about an AW4 swap.

I guessed he knew what he was doing when he posted on mating to the D300 above.
 

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This is some good info. Sounds like if I want to swap a AW-4 into my TJ I need:

'91 or newer tranny. 23 spline.
'98 or newer TCU.
connecters to mate the tranny to the TCU.

Does this sound right?
 

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Discussion Starter · #17 ·
Thanks for the info...:D

I hope this isn't getting annoying, but just to clarify:

Put in the 98 tranny with all of it's sensors, neutral saftey switch, etc, and just plug them into the 90 connectors. Modify any of the ones that changed, but continue to use the 90 TCU.

Do I have this right?

Thanks,
Jay
 

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I wish I knew for sure Jay. I'm gonna swap one into my TJ, but I think I'll stick to the '98 or newer for mine cause I know for sure that will work. I already have the shifter, pedal and other misc stuff, I just need to get a tranny and converter. Heck if you were closer I'd offer to buy you a '97 or older tranny and trade ya. It would save us both some headaches.
 

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Randal, If I were going to do it again I'd use one (AW4)without the OBDII TCU, 97 or before!
I used a 2001 IIRC in mine. I never got the TCU to interface with the TJ ECM correctly. I even tried putting the ECM from an XJ into my TJ. Even when the check engine light wasn't one it still was throughing a code and failed smog.
Problem was solved by disconecting the Sci transmit and the CCD+ and CCD- wire from the harness. 98 was the switch. The TCUs for the 98 to 2001 are compatable with 98 to 2001 AW4s.
Some things to consider. Some of the earlier TCUs had a 5 volt input vs the 12 volt input of the newer ones. I'm not sure where the cut off was. The earlier ones also have the "power" button that the newers ones don't.
From some reading although I don't know for sure the newer TCUs don't work with the manual control shifting rewiring for 1st and 2nd gears.
You can check out my write up. It was my first attempt at HTML and it is real bad but...http://www.thebassetts.us/jeep/aw4/aw4.htm
There are also a few thing that need to be updated like about the TJ manual and auto ECU info.
It was one of the first upgrades I did to my TJ and I'm very happy with it and the way it has held up.
Good luck
Bob
 

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Thanks Bob, I've read your write-up about a dozen times now. Your write-up and the one on stu-offroad are the reason I decided to go with an AW-4 instead of a TH-700r4. I might give one of the earlier models a try. I think I can find one of those locally pretty cheap. Another option I have thought of trying was a pre-'98 tranny with a post-'98 TCU. If I knew the signal voltages for the different years it would eliminate some of the guess work. I guess if I had to I could wire up a TPS from the same year as the donor XJ, but I kinda want this to be a bolt in without having to custom fab too much odd ball stuff.
 
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