torque converter lockup - JeepForum.com
 
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post #1 of 10 Old 06-18-2008, 07:35 PM Thread Starter
00XJmike
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torque converter lockup

2000 Jeep Cherokee XJ, recent RE 3'' lift and transfer case drop

My jeep is throwing a 740 code (TCC), my torque converter does not lockup. I have been trouble shooting this for quite some time. I replaced the solenoid that controls lockup and have checked for correct resistance on all the 3tranny solenoids. I have also replaced the TCM(junkyard pull). I have examined & tested the brake switch and everything looks good. As a last resort I have pulled the valve body to see if the lockup valve was maybe sticking, but everything looks good inside. I am not sure what to check next, other than replacing the torque converter itself. Jeep has only 90k on it, and other than the 'no lockup', it shifts perfect 1-2-3-4, no slipping or hesitation.

Any ideas greatly appreciated, I am all out

btw- anybody know of any gasket kits available for the aw4 valve body? seems that you have to buy an entire tranny kit to get the two valve body gaskets.

mike

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post #2 of 10 Old 06-21-2008, 07:11 AM Thread Starter
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post #3 of 10 Old 06-21-2008, 03:12 PM
jeepme95
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Can you feel the TC locking up? If it is working, you might have to clear the code with a scan tool.

95 XJ 6.5" of long arm lift, locked, 35's, warn/dutchman axles.
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post #4 of 10 Old 06-21-2008, 03:17 PM
Timo_90xj
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Check your TPS that it is working properly! Very often TC lockup problems and/ or the AW4 acting weird is caused by a bad throttle position sensor.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...

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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #5 of 10 Old 06-21-2008, 04:54 PM
irdaneel
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It sounds to me like your lock up mechanism in the TC itself has failed. It likely needs replaced. It is also possible that something is preventing the spline from engaging.
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post #6 of 10 Old 06-22-2008, 04:20 PM Thread Starter
00XJmike
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ok, I have re-assembled the valve body and installed it back in the jeep. The CEL that has been on for the past 4 mnths went off after idling for about a minute, yipee! I have not been able to get out on the highway and test it though because I have another problem.
I move the shifter to drive and the jeep doesnt go anywhere. I have to rev to about 2000 RPM to make it move foward, and it moves real slow. Same for reverse.
Any ideas? I am assuming it is something I did when I had the valve body out, guess I'll be pulling it back out. I'm gonna be a pro by the time I get this figured out.
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post #7 of 10 Old 06-22-2008, 07:07 PM
Timo_90xj
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Uumh.. does it feel/ sound like the tranny is in 3rd gear when you put it in D and try to move? What if you put your shifter to 1-2? Does it behave any different? If it starts to move much better when you choose 1-2m, then you most propably have a TCU problem, not your tranny. But of course it's possible you messed up something with the valve body.

Check your tranny fuse on the fuse panel, and the fuse close to the TCU (IIRC, also newer XJs have an in-line fuse on the TCU +12V feed very close to the connector). Also test your tranny without the TCU connected if it behaves any differently.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...

http://www.jeepforum.com/forum/f13/d...s-etc-1222317/


1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #8 of 10 Old 06-22-2008, 08:33 PM Thread Starter
00XJmike
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already tried- moved shifter to 1-2 position with and without the tcu plugged in.

I was not aware of an inline fuse close to the TCU, will have to look for that
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post #9 of 10 Old 06-24-2008, 07:05 PM Thread Starter
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adjusted the tv cable and reset the computer. put it in gear and it went into gear no problem. Took it for a test drive and everything seemed fine for about 5 minutes but then the shifting problems began- high reving before going into gear or not going into the next gear.
Any ideas? Seems as though once things warm up the problems begin.
Anybody think this could be TPS?
I really wish there was a definite way to determine whether my tranny problems are electrical or mechanical.
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post #10 of 10 Old 07-12-2008, 06:56 PM Thread Starter
00XJmike
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back to square one- jeep drives and shifts great, just no lockup of the torque converter & throwing the 740 code.
everything I've done so far-
replaced lockup solenoid & checked resistance on all tranny solenoids
replaced tcu (junkyard pull)
checked brake switch
checked all wiring from tcu to tranny
pulled valve body & checked lockup valve
cleaned nss
any ideas anybody? only other things I can think of are the torque converter and tps. I am kinda tired of throwing money at it though without knowing what exactely the problem is. I have heard that the if the torque converter is bad then the tranny fluid will smell and look burnt, mine looks fine-nice and red. I have no other shifting problems, I just dont get tc lockup so it runs at a slightly higher rpm(approx 2500 @ 65 mph). I have tried the 'tap the brake at 45 mph to see if the tc unlocks', nothing happens.
any help appreciated
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