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AW4 issue with TC lock-up

M

markaboo929

NAXJA Forum User
Location
Mooresville,NC
I have a 96 XJ that randomly the torque converter clutch will not engage. Strange thing is when it happens I can pull over shut truck off restart and works like nothing is wrong as it should.I have replaced all 3 solenoids with ATP made in USA parts. I do have a question about where the TCU gets the TPS signal from. I could not find weather the ECM provides a signal to the TCU or the TPS itself.
TPS is new napa/echlin aka. Standard Motor Parts.
Thanks
 
markaboo929 said:
I have a 96 XJ that randomly the torque converter clutch will not engage. Strange thing is when it happens I can pull over shut truck off restart and works like nothing is wrong as it should.I have replaced all 3 solenoids with ATP made in USA parts. I do have a question about where the TCU gets the TPS signal from. I could not find weather the ECM provides a signal to the TCU or the TPS itself.
TPS is new napa/echlin aka. Standard Motor Parts.
Thanks
Click to expand...

x2 on checking the brake light switch first. On a 95, it's a single switch and the TCU senses power to the brake lights. Try lifting the brake pedal with your foot when this happens too. The TCU and the ECM are both directly connected to the signal wire from the TPS.
 
Thank you for the replies. I think I might just order a new Switch because hey it's a 96. Still has the original one in it. Thank you about clearing up the TPS signal. It's just hard to explain why when it happens and the truck is shut off and restarted the problem goes away leading to tell me something is resetting.
 
Very true. It should come off easily. I had to adjust it when I bought the jeep 4 yrs ago. That's when I saw it was new/clean looking. I did not take it apart though.
 
Nope that wasn't the problem. When it doesn't like I say I can shut the truck off and restart it and works fine. Even when it acts up I would unplug the TCU and plug it back in while driving and it has no effect. I think I'm going to go ahead and order a used TCU.
 
However just because of solenoids or new doesn't necessarily mean that good. Funny thing is it's not just a TC lock up that act strange it doesn't feel like it shifts correct either what happens in all ranges.
 
markaboo929 said:
However just because of solenoids or new doesn't necessarily mean that good. Funny thing is it's not just a TC lock up that act strange it doesn't feel like it shifts correct either what happens in all ranges.
Click to expand...


That points to the TPS being an issue, except doesn't quite explain why turning off and restarting helps.
 
Tried 2 TPS and no different. I am going to do a live diag. while my GF drives. When it happens I'll disconnect the TCU and see whats up with the solenoid ohms and all other such as confirm tps signal has no loss as well as brake input etc.. Aggrivating as something resets. Not the TCU cuz I've unplugged and plugged it back in while driving has no effect. Only when the key us shut off and restarted.However it still could be bad. Tomorrow testing begins.
 
Solenoids are @ 13.5 ohms up to temp.Both 12v circuits never lost +.Ground as well . TPS stayed good.Brake was never stuck on.NSS works as should.2 remain,the TCU and trans output shaft speed sensor.I just may get a TCU & speed sensor.That's all about it really.
 
Level full. Cable adjusted correctly.I can unplug and add 12v to sol 3 control and it works. I recieved a replacement TCU today . I am going to install it tomorrow and road test. It has been an intermittent issue. I will post results after a few days to see if it corrected the problem. Indicating my hunch of a TCU going bad
 
its possible that it has a bad solider joint in the tcu and loosing the ability to enable the solenoid.

unless you have a bad wire going to the transmission from rubbing. and the starter torques the engine just right to get it to un short. just spitballing ideas

aside from getting a scanner that can read live data from the tcu to see if it is indeed engaging the TC
 
It also has weird shifting in all gears when it acts up as well. I checked all wires from TCU to connector and to trans.Having it reset when shut off and return to normal suspected the TCU.Temp has no effect difference.Im speculating internal power relay of TCU.
 
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