zpsull01

1996 Jeep Cherokee Sport, 4.0L AW4 trans, 4x4. 23x,xxx miles.

Been fighting a shifting issue for the past year or so. Seems to mainly do it when driving at highway speeds for more than 5 miles or so. will jump to anywhere between 2300-3500 rpms at about 55 and wont shift. Dropping it into 3rd manually actually lowers engine rpms to around 2200 or so. seems like the convertor isn't locked up. Most of the time have to drive at a lower speed, 25mph or so for a few minutes to clear the issue and it drives fime again for a few minutes until it happens again. Have had it to two trans shops with no luck.

First place said either the convertor or the solenoids in the trans were bad. I replaced the convertor with no luck and checked the ohms of the solenoids at the pcm plug under the passenger side dash and they all checked out ok. Did a little research and found tps issues with simular symptoms. Replaced the TPS and no issues for a few weeks before it slowly came back around and is back to fully acting up again.

Second shop checked out the electrical side and informed me that the TPS was staying on level 3 and 4 when it is actually at a lower level. They said this was causing the trans to try to go into passing gear. They said that either the TPS could be failing even though it is only a month old and they want me to replace it with an oem unit. I have a cheap rockauto unit in at the moment. They also said if that doesn't fix it they would replace the engine ecu since it isn't reading properly. What would you do or check next? I'm at a loss with this thing.

Thanks,
Zack

AirborneDeth

Sounds exactly what happened to my ZJ. The transmission blew soon afterwards.

zpsull01

Both shops agreed that the trans had nothing wrong with it and that it was a control issue. The jeep isn't throwing any codes besides an O2 sensor either. Are there any tests that I can do to check the circuitry of the TPS system? I have a spare AW4 out of a 97 sitting in the garage but I've been hesitant to swap it since everything is leading to the controls side.

Also if it comes down to it will the 97 trans work in the 96? I know that they made some changes in that time frame.

94xjse99xjsport

Sounds like what my 99 did, so I don't know if it'll help you. I was driving one day and noticed the transmission shifting in and out of overdrive. I drove home and the transmission fluid was burnt. I put a low mileage trans in and it did the same thing. After a lot of searching I replaced the brake light switch on the pedal. I never noticed it before, but when you are cruising around 55 mph and tap the brake, it unlocks the torque converter. I was pretty upset when I found out I put the transmission in for a 15 dollar switch Might try that switch.

cruiser54

I'd be checking the same thing myself.

And, doing this 5 minute job:
Cruiser’s Trans Plug Refreshing

Over near the trans dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and trans solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.
Revised 3-28-2012

cruiser54

Unfortunately, your ZJ didn't have as hearty a transmission as the AW4.

Thanks for the encouraging words though.

AirborneDeth

My ZJ had the AW4.

cruiser54

What year and what engine?

AirborneDeth

1993 ZJ with the 4.0, AW4, and 242 TC. I loved that thing but I was sinking too much money in it after the tranny let go.

stock95sport(for now)

only avail like that for half of '93. rare one there still ZJ's are heavy pigs and tax the trans harder.

AirborneDeth

I didn't know they were so rare.

BTW, I have a really good friend from Tilton, NH, and visited there a couple of years ago.

zpsull01

Thanks for the help, I'll clean the connectors and go ahead and replace that switch.

cruiser54

I kinda remember that now. I left the dealership in October of 1992.

stock95sport(for now)

Tilton is nice NH is nice, but not "wheeling friendly" which sucks. I have a Cousin at Shaw AFB, SC. Well works there, lives off base. Im planning on visiting him, im sure ill pitstop in NC!

stock95sport(for now)

http://www.novak-adapt.com/knowledge/aw4.htm

nice little AW4 writeup