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Problems with the aw4

Jbaddick17

NAXJA Forum User
Location
PA
Lately I’ve been having some issues with my aw4 in my 96 Cherokee, sometimes it will shift perfectly fine and other times the issue comes when I’m in OD, converter locked. When I let off the throttle the TCC should unlock to allow the Jeep to coast, and then when you get on the gas it should rev up a few hundred rpm and re lock, mine just doesn’t unlock, and won’t unlock unless I hit the brakes enough to trip the brake switch, or slow down to 30mph and then it comes out and down shifts. (Things I’ve done) new eichlin tps from Napa, tried junkyard tps and many other ones, adjust kick down cable, every which way, changed the tranny fluid 5+ times, cleaned all connectors for trans and added dielectric grease. I have no CEL’s and I am pretty knowledgeable when it comes to the xj, but this has me stumped and it’s getting on my nerves at this point, this same exact issue is why I sold my last jeep, so please help me out, thanks guys!
 
There is an AW-4 Diagnostics and Service Manual that can found on-line with some searching, do you have a copy of that and/or a copy of the Factory Service manual ?

Dexron-III/Mercon and NOT ATF ? Tested the solenoids ? Tested the transmission speed sensors? Cleaned and adjusted the NSS ? Swapped in a junkyard Transmission Control Unit ?
 
TPS would have been my first guess, but you've changed that already. I would inspect the wiring harness from the TPS all the way back to the firewall. I've been hearing of a lot of people lately where the wiring is chaffed or fatigued where it crosses over from the engine to the firewall. Do cruisers suggestion of cleaning the connector at the trans computer, andwhile you're there check the resistance of the solenoids and measure the voltage of the throttle position sensor input while you exercise the gas pedal. I'm thinking the TPS can be good, but wiring between it and the computer could be bad. No other driving symptoms of a bad TPS?
 
No there is no other symptoms of a tps failing, had a random high idle and traced it to a vacuum leak where the manifold bolts to the head, tightened those bolts and haven’t had that issue since
 
So I had time to test the solenoids them selves, looking at the engine bay connector, from top left to top right (13.3) (13.3) (13.8) those are my 3 ohms readings at the trans connector, rest is O.L.
 
Drove the Jeep for a 15 mile drive so that everything was hot and then re rested my shift solenoids, readings are from top left of connector to top right, starting with white and black wire 14.9, 15.2, 16.1 ohms
 
Forgot to mention I tested the tps, has a good ground, 0.01 ohms there, 5.17 volts going in, idle has .43 volts and full throttle reads 3.9 volts
 
If you ask me, that TPS is out of specification.

The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. This will vary in an approximate range of from .25 volts at minimum throttle opening (idle), to 4.8 volts at WOT wide open throttle.

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics. The TPS function should be verified early in the troubleshooting process, when a transmission issue is suspected.
 
I thought it was out of spec as well but I have tried literally 15 different tps sensors, junkyard used and brand new, tried advanced, autozone, and now Napa and can’t remedy the issue
 
I got bored today and decided to mess with it some more, I took a few of the other tps’s I have and tested them without hooking them to the throttle body, full sweep on them ranges .27 volts to 4.75 volts, which seems more like it should be, so why when they are attached to the throttle body do they read incorrectly? Messed up throttle body? Or can I egg out the holes to be able to rotate them to get the correct readings, basically making them adjustable.
 
get Nick's Renix Engine Monitor. you can read all sensors live as it runs. you can set the TPS and watch the screen and tighten it at 17. no probing etc. he charges a little over 100 bux for it. Nickintimefilms on youtube.
 
get Nick's Renix Engine Monitor. you can read all sensors live as it runs. you can set the TPS and watch the screen and tighten it at 17. no probing etc. he charges a little over 100 bux for it. Nickintimefilms on youtube.

I don't think the Renix Engine Monitor speaks OBD-II...
 
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