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Old February 6th, 2004, 16:58
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tweedles tweedles is offline
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Angry Transmission Problems

I have an 89 XJ with a 4.0 and the AW4 transmission. Here's my problem. The other day I lost all forward gears. They didn't go over a couple of months or weeks, but in one day. The gears started skipping out. It would take me a while to get rolling until something would grab and I would jet off. After getting going, the tranny would shift a little on the slow side and if I gave some gas to pass, the gears would skip out and the transmission wouldn't engage.

Here's what I've done for trouble shooting:

I still have reverse functioning normally, so I don't think it's a tourque converter problem.

I adjusted the TV cable as per Haynes manual.

I checked the TPS voltage and all is good.

I changed the transmission filter and fluid. The ATF was a little dirty, but there was no sludge or filings in the filter or oil.

I checked the shifter linkage and it is adjusted properly.

I tried manually shifting the transmission into 3rd and OD by taking out the fuse I have in the yellow transmission wire.

I am using Dextron-Mercon III so there isn't a problem with the fluid.

Does anyone know what can cause this kind of behavior. The guys in my Jeep club don't know much about the AW4 and I don't want to dump a bunch of money into replacing the transmission since I bought the XJ for $500.

Any input would be helpful.
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Old February 6th, 2004, 17:27
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CaptTrev CaptTrev is offline
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Quote:
Originally Posted by tweedles
The gears started skipping out. It would take me a while to get rolling until something would grab and I would jet off.
well, i'll be the first to admit I'm no tranny guru--there are much better others on here than me---but i'll see if i can throw anything on the table....

being that this happened all in one shot, just in one day, im going to guess electrical problems.

and when your quote from above about going slow and then all of the suddeen it will "grab" and pick up speed....

I'm thinking maybe you lost 1st and 2nd gears?

perhaps the shift solinoids went bad?

you mentioned the TPS checked out ok. did you check the TCM (tranny control module aka ECM engine control module)

it is a black box locacted (on my 96) under the glove box, under the plastic trim by your knees.
look up the Ohm (resistance) values and do a meter reading on it to see if its still good.
it could explain why all of the sudden this went bad

other than that...im sure you checked all fuses for everything??

good luck!

hopefuly other will chime in with more and better ideas

HTH

CaptTrev
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  #3  
Old February 6th, 2004, 17:36
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Eagle Eagle is offline
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Tweedles -

You said you tried shifting manually by removing a fuse that YOU HAVE in the yellow wire?

Are you referring to a factory fuse, or something you rigged up to address some other problem or perceived upgrade?

What happened when you removed the fuse? One of the factory procedures to troubleshoot the AW-4 is to remove the fuse for the TCU and shift manually. Going from memory, I think that's supposed to work except you lose either first or second gear. However, if it goes in the forward gears and doesn't skip, that would suggest a TCU problem. If it doesn't work with the TCU disabled, the problem is mechanical.
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Old February 6th, 2004, 17:54
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tweedles tweedles is offline
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When I bought the XJ there was a fuse spliced into the Yellow wire that runs into the ECU. I was told that if you were to splice a switch into that wire you could effecivly "hold" a gear or in other word bypass the ECU and make the transmission shift into 1st, 3rd or 4th. I was trying to duplicate that by removing the fuse that had been spliced into the wire and forcing the transmission to shift to third or fourth.

Since this doesn't work, should there be some signs of something mechanical in the old fluid, like metal filings, debris, sludge, etc. When I pull the pan, there was no buildup or sludge or filings anywhere. As I said the fluid was discolored but didn't smell burn't. Also, wouldn't a mechanical failure be fairly progressive, like over a periond of a couple of weeks or months. My tranny went from excellent to shot in a half-hour of street driving.

As a side-note...

I'm running 31's on no lift with a lincoln-locked rear. Would the added stress of these mods take the tranny out?

Last edited by tweedles; February 6th, 2004 at 18:02.
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