Torque converter unlocking
 

I have a 92 Rs 700r4, what started last week was i was driving my car starting from cold, as the car warmed up the converter reached the point where it normally does to lock after heating up, but it began locking and unlocking, lockin and unlocking, i smashed on the gas, it went away. later on the same night as the engine got, normal operating temp and 40 45 mins of drinvg the torque converter won't lock in 4th. ocassionally it will lock or if you play with the gas pedal, leting off starting again it locks. this has been happening on and off. In the mornings, every morning after it passes the 120 mark for the converter to lock up it works absoloutely fine the converter locks like its supposed to everytime for a good half an hr. but then in the warm afternoon after say about 30 mins of driving or bit less with the car hot the converter starts to act up again and simply doens't want to lock most of the time when its suppose to in 4th gear going over 45, 55+. i don't know what it is any ideas?? i believe its electrical, i hooked up the test light to the D terminal on the ALDlink, it does manually lock when i make contact to ground at least this morning it was working ok, even after it shifts to gear 2nd i can manually lock it. please help! btw i haven't changed fluid or anything recently no sensors either. orig eng trans. i've owned the car for 9 years.

Re: Torque converter unlocking
 

If you can lock it through the ALDL there are no electrical problems.

What's your coolant temperature when it's locking and unlocking?

Re: Torque converter unlocking
 

ok i did some more testing when the converter is acting up/ not wanting to lock all the time, it cleary also doesn't want to lock when i use the manual overide/ground the aldl D terminal at the same time in 4th. it either wont' lock when its grounded in 4th or it will lock on its own ocassionaly or after playing with the gas in 4th. the temp is around reg operating about 190, 180 mabye 200 after taking off from sitting at a light.... The test light on the D terminal turns on when i hit the brake, let off the accelerator completley, but thats' normal....

Re: Torque converter unlocking
 

ok i also found the auto trans wiring diagram specficaly for 92 throttle body it has a temprature sensor in the tranny too, http://www.austinthirdgen.org/mkport...8_vinE_TCC.jpg

it is hard to change the TCC solenoid, 4th gear switch and this temp sensor? i'm thinkin that might be the prob, one of those things.....

Re: Torque converter unlocking
 

The temperature switch in the transmission will force it to lock up if the fluid is overheating. It can't prevent it from locking up in normal conditions.

Re: Torque converter unlocking
 

ok so then it probably isn't that, i see or found the solenoid is easy to change to 2 bolts, right in front of you on the side, any ideas on the 4th gear switch? (location in trans, r&r details) what is its purpose anyways?

Re: Torque converter unlocking
 

The 4th gear switch tells the ECM that the transmission is in 4th. The solenoid is easy to replace, but it's likely not your problem.

When you put the test light in the ALDL, when does it turn on and off as the TCC is locking and unlocking?

Re: Torque converter unlocking
 

It should also be worth mentioning last friday i was running deliveries, i kept the car running most of the time, stop go, the converter was doing the same thing not locking in between them, locking sometimes.... then on my way back i hit the highway 4 lane so i set the cruise at 60 mph when i would start to come down a grade the accelerator realseses slightly to maintain speed and the converter jus kept unlocking and locking constantly like 10X it wouldnt stop till the downward grade ended i hit the brakes, then gave gas went away... it did this twice, the 2ndX when i dropped of the accelerator completely the same thing happened locking unlocking locking unlocking all around 60 65. unfortunately i didn't have the test light rigged to the D terminal in order to try to manually see if it would lock, i'll try if i get another chance

Re: Torque converter unlocking
 

when i put the test light on the only time it lights up is 1 sitting at idle at a light then i take off i get past first gear it will stay on, even tho the converter locks in 2nd no prob, the engine luggin, then it quickly turns off heading toward like 30mph 2nd if i let off the gas it turns on if i press the brake it turns on. everytime i'm giving fuel while driving its off, cept when taking off. even if the converter hasnt' locked yet in 4th or doesn't want to its off, or it locks after a few secs while giving fuel, its off... Do u have any idea what the probably is?? or exprience with this or know anyone that does, the tranny doens't slip in any of the reg gears only the converter does when its esp hott... i don't have very much exp with tranny's but i've fixed pretty much everything else on this car when it goes out... i apperciate your assistance

Re: Torque converter unlocking
 

ok i did some final testing, bascially the converter will stay locked if i take off from the light with the terminal D grounded however there are times when it will suddenly unlock in 4th even while grounded on the ALDL pin. if you attempt to ground the terminal while in 4th gear with no previous attempts the converter doesn't not lock it acts like i'm not manually overriding it, or it'll lock after a few seconds on its own, attempt to lock but fail, or not lock til u let go of the accelerator and then give gas again, then it locks all this while keeping the Aldl TCC pin grounded. i'm so confused. there are also times when the converter unlocks in 4th, on the higway 55, 60 mph while keeping the ALDL tcc pin grounded almost like its slipping, regardless of grounding the D pin. is this normal should it unlock like that?????? even while i'm closing the circuit/overriding the ECM?

Re: Torque converter unlocking
 

Was there ever a fix found for this?? Im having the exact same problem.

Re: Torque converter unlocking
 

unfortuantely i did not find a fix, i ended up driving the car like that till summer 2 years ago in 2016 i sold it with over 305k on it.
the problem was either the lock up switch inside the transmission or it was just starting to lose pressure, the car still ran tho and i drove it on a 2000 mile trip across country, no issues. original engine and trans.

Re: Torque converter unlocking
 

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