View Full Version : TCC giving me trouble, help!!

03-29-2008, 10:19 PM
Hi guys, my name is Jim and I'm new here but I'm very happy to have found this site.

I'm an avid fan of Chevy Celebrities, and right now own a 1986 2bbl wagon Eurosport with the 440T4 Tranny/2.8L engine. Recently (aka January) my torque converter clutch is acting really odd. It will engage like normal for about a minute until it seemingly reaches closed loop stages, but after warming up it will disengage, then re-engage again, about 15 times in one minute. I do a lot of highway driving so I paniced when this started to happen. Since then I unplugged the TCC and have driven around just fine since then, but I won't allow myself to drive faster than say 58 MPH because I know the connection is weak.

I've given my car a full tuneup as well as a precautionary thing to see if maybe a misfire was the cause, since before the tuneup it would die all the time under harder acceleration. After the tuneup, it will still die at idle occasionally and act like a piece of crap once warmed up, but acceleration was fine.

Long story short, I want my full lock up back! When I have it plugged in, it runs like an absolute charm until it starts to disengage. I've been told it's probably a speed sensor or ECM and I plan to fix this at any cost now. Thank you very much!

03-29-2008, 11:39 PM
Sounds like its looking line pressure inside the tranny. Whens the last time you gave your car a tranny service?

03-30-2008, 01:30 AM
August 2007, new fluid, filter, pan, and seal.

03-30-2008, 01:56 AM
Jimbo, try this: When it does its crazy engauge, disengauge thing:

Lightly hold down the brake pedal while still holding on the gas. If the craziness stops, then your problem is the TCC Lockup Solenoid (sp). If it doesn't change with the brake pedal lightly applied, then it could be something a little more internal.

Our transmissions weren't electronically controled until the 4T60-E came out in the early 90's. And they were controlled by the PCM, not the ECM. Since your car has the carb, I doubt your ECM needs replacing.

03-30-2008, 02:15 AM
There is a pcm AND a ecm??!?! I know the ecm is in the glovebox where the pcm???

03-30-2008, 07:43 PM
There is a pcm AND a ecm??!?! I know the ecm is in the glovebox where the pcm???

They're two different names for a similar type of device - ECM is Engine Control Module, while PCM is Powertrain Control Module. The latter is usually used for newer computers that control not only the engine, but transmission or transaxle as well. A car will have either one or the other. The computer in your Celeb, as it only controls the engine functions, not the shifting of the transmission, is referred to as an ECM.

03-30-2008, 11:36 PM
Whoops, so I misspoke up top a bit. I never realized it was an ECM or a PCM

04-01-2008, 04:57 AM
How big of a repair is the solenoid? I'm pretty sure my buddy had me do that test one time of holding the brake pedal down lightly as I was going along at like 40 MPH and it stopped it's craziness. My huge GM manual that I have says that my computer controls the TCC, hmmm.

04-01-2008, 04:58 AM
Also, why would it only act odd like that when it's fully warmed up? Wouldn't that lead you to believe it may be related to the ECM?

04-01-2008, 05:20 AM
It could be a bad TCC, or it could be a bad tune up on the engine. Personally, I would have to look at everything here. A bad tune, bad coil, bad plug, bad wire, or a bad TCC, could all cause this, and act the same way.

04-01-2008, 05:38 PM
Also, why would it only act odd like that when it's fully warmed up? Wouldn't that lead you to believe it may be related to the ECM? No the tcc only engages when the engine is at operating temperature. If your at 60 MPH and the cars cold it wont engage.

04-01-2008, 05:53 PM
No the tcc only engages when the engine is at operating temperature

I think it depends upon which GM setup you have....earlier ECMs did this...but later ones, this rule may not apply.

To go into closed loop only requires a temperature of around 100 degrees F, engine temperature, if O2 has a good signal, and if enough time has passed....and in closed loop, the TCC will engage if vehicle is at some speed, with light load.

04-02-2008, 01:47 AM
As soon as the car starts to warm up, we'll say 120 degrees, it engages and stays engaged for a little bit, maybe 3 minutes. Then when it reached full operating temperature (est 170 degrees), it starts to run wild. It does this even in the lower "4th gear" between 30 and 35 MPH as well. I tell you this bothers me more than anything in the world!

04-02-2008, 06:27 AM
This sucks, I just put in a new ECM and now the TCC won't even engage at all even plugged in, what the heck? :(

04-02-2008, 02:09 PM
I know this isn't your exact problem but many of these TCC's would stay locked as you came to a stop and kill the engine. It happened to mine. Here's a good article about it:


I just unplugged mine, haven't gotten around to fixing it yet.

04-02-2008, 02:12 PM
Hi Jim. Do you have a scanner? You should drive with the scanner hooked up and look at the readings while the fault is happening. I would pay particular attention to the Coolant Temp Sensor. It may be fluctuating and causing the TCC to disengage. The only way to tell for sure is make it happen and look at all the factors that effect the TCC on a scanner.

04-02-2008, 06:30 PM
No the tcc only engages when the engine is at operating temperature.

Best info I can find:

in $A1 i have 3 closed loop enable timers, cold, warm and hot (http://60degreev6.com/forum/showthread.php?t=39995)

Cold is 180 sec
Warm is 110 sec
Hot is 40 sec

I believe those are stock values as well.

I also have:

Max coolant temp for Cold C/L timer as 14.75c
Min coolant temp for Hot C/L timer 70.25c
Min closed loop coolant temp is 39.5c which is 103.1F

In other words, engine has to be above 103 degree F for this vehicle to be in closed loop (if 02 Sensor is working) so that TCC could be engage, if right speed and load are OK.

04-02-2008, 06:51 PM
Perhaps, i do recall reading that a 88 ciera 2.8 will not enter cold loop until 130. i do not remember reading anything else, for any other car however.

I do know that a defective or not fully seated CTS will cause intermittent or not at all TCC lockup (as don mentioned)

A scan tool here is probably the best thing to start with.

04-03-2008, 02:43 AM
A scan tool here is probably the best thing to start with.

Test light hooked to TCC wire will work just fine; sometimes, people don't know what lockup means, or how to perceive it when it happens.

04-03-2008, 03:06 AM
I got all the manuals and stuff for it, and I remember my buddy telling me a thing you could do with just a paper clip. What terminals do I put these in?

04-03-2008, 03:39 AM
Uhm not positive on the celebrity. But if you look under the dash you should see a plug with a cover on it saying 'diagnostics' iirc.

Anyway, remove the plug, and with the paperclip (or wire) jump the two upper right terminals.


You will want to jump E to F. The SES light will flash out any codes, 12 is a diagnostic code, ignore it.. And the cooling fan should come on.

In addition, if you do this while running, the SES light will blink rapidly if the car is in open loop or slowly if in closed. In order to get codes, car off, ignition on.

It sounds like the solenoid itself is bad though, since it's been inactive and now doesn't work at all. Test light at the connector was a great idea.

04-12-2008, 06:42 PM
Wow turns it this was all related to a faulty ECM after all. I didn't have my PROM pushed in *all* the way when I did get my new ECM. All is fixed! Thanks guys!