AW4 electrical problems.

I have been reading and searching for common AW4 electrical problems for the past week and I am stumped.

I have a 1996 Xj with an aw4, 33" tires, 4.5" lift and stock 3.55 gearing. For some reason my cherokee started shifting funny after getting a little hot in stop and go traffic. I figured out the problem was the fan clutch, I replaced that and also added a tranny cooler. This solved all my cooling problems but It's still shifting funny.

Here is what I have done and tested so far, Brak light switch, I tested 1v with the brake off, then 12.6v with it on, so I replaced it. Now I get 0 when off and 12.6 with it on.

Replaced all fluid, color was a little dark but did not smell burnt at all. Now it's red and clean, still no burning smell.

I replaced the TPS with a new one, I have a 1996 so it's not adjustable.

I adjusted the tranny cable on the TB, I pushed the cable all the way in and then hit the pedal to WOT and heard several clicks as it adjusted into place.

I tested the ohms of the 3 solnoids and they were all within spec, about 13 ohm.

I can unplug the TCU and shift just fine manually, but the TC never locks up and also skips 2nd gear I believe.

The speedometer works fine, and I can see the voltage pulse when the DS is rotated.

Right now it currently will not downshift when I floor it on the highway, and the torque converter will only lock when accelerating on the highway. When I am cruising at 60mph it stays unlocked, then as soon as I hit a hill the rpms drop and it locks.

Please throw some ideas at me of what to check. Im lost, Im about to make a manual torque converter lock so I can at least lock it while on the highway on my way to work until I figure this issue out.

Well, because it works fine with the TCU unplugged you know that most, if not all, of the trouble is electrical.

Try adjusting the TV throttle cable and test the TPS with an analog multimeter. If you use a digital multimeter your reading will probably be skewed due to the buffer ciruits built into the digital meter. You want the test for the correct voltage and also test the full range of the TBS as the throttle is moved troughout its range, looking for erratic readings that indicate "flat spots" in the TPS.

no, first get a trans computer from the junkyard.

is there any difference before and after you did the tb swap? it it was doing it beforehand the cables and your new tps are not going to be the main problem

I didn't do a TB swap. There was no difference before and after the TPS swap if that's what you mean.

The problem hasn't been consistant which is making this hard, sometimes it works fine and sometimes it doesn't. Like this morning it was fine for the first 30min of my commute, then after being on the highway for a few miles the torque converter unlocked and would only lock again if I was going up at hill.

sorry to hi jack but how do you know when the TC locks and unlocks? new to the aw4 system?

I am having the EXACT same issue with my AW4, its pulling a shift solenoid B P0756. Can you tell me where the TCU is? Mine is a 97 XJ BTW.

On my 1996 Its under the glove box behind the plastic panel.

You can usually feel it lock, the rpms drop, I know mine is locked bc I know I should be at 2100 rpm in 3rd at 55mph on the speedo (64 on the gps) I usually don't run in D on the highway with my 33's and 3.55 gears.

What's strange is the past 2 days I haven't had any problems with the aw4, it has been acting just as it should. I'm going to go through all the wiring, there has to be a loose wire or short somewhere.

There has been a link to a document posted many times that outlines how to test the wiring harness for the AW4 to help narrow down the problem.

Start there.

I had the exact same problem with my 96 XJ.

Went to the JY and pulled about a half dozen TCUs.

Plugged one in and it shifted fine.

I still have about four sitting in the garage. I'll send you one for $15 shipped if you want. Just let me know.

MrSimon said:

I had the exact same problem with my 96 XJ.

Went to the JY and pulled about a half dozen TCUs.

Plugged one in and it shifted fine.

I still have about four sitting in the garage. I'll send you one for $15 shipped if you want. Just let me know.

Click to expand...

Ok thanks! I will let you know if the problem comes back. Right now I'm thinking it's a short somewhere since the problem magically went away. It's been fine for the past 3 days, 240 miles or so. I'm guessing there must be a bad connection somewhere that wiggled itself loose and is now working again.