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update on torque converter probs...

qwickcrx

NAXJA Forum User
Location
So. Calif
Have an '89 xj and the torque converter is locking and unlocking intermittently only in the hottset part of the day. Never in morning, never at night, and not even while towing, unless in the heat of the day. It doesn't happen every day and only happens in 3rd and 4th gear only between the speeds of 40-55 mph. When it does act up I simply turn the ignition off and then on again while driving and it seems to drive normal again. Took it to a tranny shop, and to the local Jeep dealer and they say most likely electronic but that they cannot diagnos the problem. Also cruise control works sometimes and other times it wont hold a steady speed.

Fixed two mainfold vacuum leaks and problem seems to have gone away but cruise control still acts up intermittently...more leaks maybe?

Any input ....anyone? anyone?
 
Hummmm. No one's responding. I will say this- Cruise control probs can be a real hassle. Do the obvious and ck all connections totally well. Intermittant probs many times are the result of bad grounds, where ever thay may be for that system. Sorry i don't know more specific info. Ck the vacuum connections to that also. And make sure the trans fluid is in good shape. Good fluid pressure also is involved in good torque converter lock-up holding pressure so you need to try to keep the pump in fairly good condition. A number of variables are involved in the torq converter operation...more than just electric. Is it locking/unlocking? Or slipping...
 
I don't have the answer to the torque converter problem, but I can suggest a work-around. There have been methods posted here from time to time on adding a switch to manually control torque converter lockup. One of the guys in NAC (North Atlantic Chapter) has an '89 that apparently had not been locking ever since he bought it used several years ago. He added a switch and now he has lockup when he wants it.
 
Usually problems with the aw4 shifting 3 to 4 and back and perhaps torque converter are caused by the TPS (throttle position sensor) being bad or out of adjustment. Pre 91s are adjustable. When mine did the wacky shifting back and forth at highway speeds yrs ago it was the tps out of adjustment. Also check for a bad ground signal at the tps ground wire. Note your tps has two connectors one for engine computer and one going to the tranny computer (tcu). Good Luck. Greg
 
what vacuum lines were leaking cause mine does the same thing.
 
Mine was acting strange for various reasons, the diaphram in my EGR valve was leaking, causing a vacume leak. The heater control vacume line was leaking near the resivoir. And the TPS, was acting up, finally figured out there was oil in the connector, adjustment values kept changing (most of the problem).
Remember reading about, TPS voltage problems at 1/4 to 1/3 throttle, causing, lock unlock. Solution was to change out the TPS.
Think I still have some vacume issues, but seem to be gaining on it.
The TCU, grounds to the dipstick bracket on mine, cleaning the grounds, changed my shift points. Cleaning the ground between the head and the firewall, smoothed out my idle and also seemed to affect shifts.
There is, I´d guess a capacitor, in the TCU, on the TPS ground circuit. If you have a good, voltage meter, you can test for standing voltage in the TPS ground circuit. I had about half a volt of current in the TPS ground wire, until I cleaned every connector between the TPS and TCU.
The vacume leaks, might or might not have contributed to the convertor locking and unlocking, but the loss of torque and the miss from the vacume leak, seemed to magnify things´.
 
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I am thinking TPS on this torque convertor issue because the brake switch makes it unlock and coasting to 1100 RPM unlocks it and pushing the pedal hard enough makes it unlock and downshift. The speed sensor is OK (speedometer still works with no glitches) and the brake pedal is OK, and the map sensor(for decelerate) is OK and NO CODES!!! I have a good ground and full 5 volts at the sensor(I assume when I am not moving) but when I reset the computer by pulling the fuse, it won't act funny for three or four drive cycles. Do you think that if there is a wiring problem with the TCU or TPS it would cause this intermitent problem? I want to get this right cause I want to install the TCC lock/unlock and 1-2 eliminator switch soon.

I checked the service manual from the dealer and I can't find what must happen in order for it to unlock, besides pressing the brake pedal. All I know is that it used to unlock every time I took my foot off the gas it would unlock and now it doesn't. I also put in a different TPS and it didn't change anything...............
 
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