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AW4 issue with TC lock-up

Following this thread closely as I have had TC lockup issues as well. Curious as to whether your troubles ever set a code..

BTW, at one point I got tired of suspecting the TC solenoid as well as the TC itself, so I tapped into the lead that goes to the lock-up solenoid to apply 12VDC to the solenoid lead. -- got the 12vdc from the cigar lighter. With the lead plugged in to the cig lighter the TC locked up tight, thus letting the solenoid and the TC off the hook.

I am, however, still wrestling with code P0700 which sets occasionally if I drive my XJ in 'D'. If, however, I leave it in '3', it never sets that code; and of course, the TC does not lock.

All of that crap said, my XJ drives and shifts quite normally, including the TC locking up as it should. Well, with this one exception: the damn check engine light illuminates after 6 or 7 miles, and won't extinguish until I kill it (the light) with my cheap-ass scanner. And the XJ shifts perfectly -- along with TC lock up -- even with the "check engine" light blazing away.

Hence my question as to whether your Jeep is setting a code.

So far, it's the best case for a little piece of black tape that I have seen. But that would not assuage my OCD that makes me want every thing on my XJ to work correctly.

Please continue to publish your activity and I do hope you soon solve your issue.
 
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I am not as familiar with the pre '98 Trans. Not really an expert on the latter either. Still, I had issues with a '98 trans. I replace the Solenoids, new NSS etc. Did a trans shift kit. No, luck. I had a neighbor bring his computer from work. Couldn't find an issue. He said to change the speed sensors or the rear one. I replaced the rear speed sensor and it worked.
The '98-up has two speed sensor (not counting the MPH sensor). I think the 97-down has only one.
 
Installed replacement TCU and drove about 30 miles highway and streets. So far ok but time is the real story teller. I'll update again. No codes were ever flagged during all this. Last thing is speed sensor for output shaft. At least I see a new one can be had.
 
I've never seen a speed sensor go bad myself, although I have seen the wiring get damaged. If it's bad, the trans computer just thinks the jeep isn't moving and will stay in 1st gear
 
markaboo929 said:
Installed replacement TCU and drove about 30 miles highway and streets. So far ok but time is the real story teller. I'll update again. No codes were ever flagged during all this. Last thing is speed sensor for output shaft. At least I see a new one can be had.
Click to expand...
So your torque converter is now locking up?
 
So far so good.I found I can disconnect the TCU and directly power the sol #3 no problem.It is/was an intermittent issue. Today it is working no problem if no issue in 3-4 days then the TCU was bad. Previously it happened every day or 2. Time will tell
 
Okay here's an update I have replaced the TCU with a used one and it seemed fine for a 2-3 days so I went ahead and replaced the output speed sensor in the tail shaft area. Today it is actung the exact same thing again all of a sudden it seemed like the transmission started slipping torque converter not engaged pulled over shut it off start a backup problem went away. At this point I am more and more proving my theory that when electronics are introduced into an automatic transmission Nae Nae. I've known for a long time that a manual transmission beats automatics every single time.Any ideas now whay?
Maybe go the AW4 shifter mod so I have control and nit ?
 
Do you have Cruise Control? Just wondering as I think the Cruise Control shares the same circuit as the TPS. Also, any issues with the battery and battery cables?
 
No the battery and battery cables are fine. Yes it does have cruise control however I think that the ECM just engages in cruise control is needed which the signal from the TPS would go directions to ecm and I have not yet found a good wiring diagram that shows specifically where the split is for the TCU TPS connection.
I have a spare ecm i might try just for the hell of it
 
I would carefully inspect the wiring down to the trans for damage. I've seen a few reports of the wire getting chaffed under the clamp that hold it to the side of the trans. Scrolling back, I see you already addressed the NSS.

How you tried popping the shifter between neutral and drive without restarting when it happens? If that fixes it, that might point to the NSS being the issue. Brake lights not staying on?
 
Replaced brake light switch. When I replaced the trans speed sensor,single type,I checked the wiring at the clamp.I tested all signals as it was happening no issues.I can see whether the TCU turns on the TCC solenoid via test light connected. It will not engage the solenoid when it happens. I really need the wiring layout to see where the TCU gets power from it maybe a relay that is a suspect. Ive had them let go of the coil when hot then release when it is shut off and returned to operation...repeat issue.
 
Interesting thing is when checking the solenoid resistance with tcu disconnected they check good. However when the key is turned on the resistance is higher than normal,but works fine until it says eff you.
 
Did some diag yesterday n today.When the issue happens I checked the signals again. No tps acting up,brake light ok,solenoid power engauged,added a ground no diferent. As before replaced all that is related. New question is can the lock up section of the TC be bad and not the normal function of it ok?
Did not have any problems for the 2 years since I swapped to a 4x4 trans. Previous owner said it was a rebuild I believe them that it was due to obvious silver cheapo paint job and black silicone on pan and adapter. Factory is Toyota red.
 
markaboo929 said:
Interesting thing is when checking the solenoid resistance with tcu disconnected they check good. However when the key is turned on the resistance is higher than normal,but works fine until it says eff you.
Click to expand...

Measuring the solenoid resistance with the connector plugged in and power on is going to give a misleading result.
 
When it gets a little warmer out I'll take the trans harness inside and pull it apart to clean ,inspect. If it was me driving it,I am a double amputee and blind in one eye,It would have the NV3550 trans out of my 88 in it in the first place.
 
Ya know I think it may be the overdrive clutch not engaging. It passes all electrical tests. It happens when hot trans randomly like it shifts out. Well I'll test tomorrow the manual way when it scews up. I will also power the TCC manually as well. That goes on my judgement of if I don't rebuild things myself...I do not trust. It's been good for 2 years,but still a rebuild should last just as long as the factory one. IF done correctly.
Uggg...I'll also go the Lucas route to see if it improves.
 
The lock-up clutch is in the torque converter so it's hard to say!
 
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