lock-up torque converter intermittently fails to lock-up

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I have a 1996 Pontiac Grand AM SE with the 2.4L twin cam engine. It is a four speed automatic trans. with overdrive (IE..lockup torque converter). Here recently I have been having a problem with the torque converter not locking when it is supposed to at speeds upwards from 50-70 MPH. The transmission will run through all four forward gears and then you will feel the torque converter lock like it should until you get what seems like some miles on it and the trans. temp up. I am not sure if I can 100% for sure say that this will only happen when hot, but that has been the case thus far. Once the transmission has gotten hot and this could be 20 miles or 60 miles down the road, all of a sudden the transmission will not engage the torque converter to lock up so it stays in fourth all the time. This means that when I depress the gas, I have instant power and acceleration and I should not, I should have to punch the gas a little to knock out the locked torque converter so that I hit drive range 3. This is causing the CHECK ENGINE light to come on and poor gas milage. I am trained in automobiles and have worked on them for years but my knowledge of auto transmissions is not as detailed. Now, you can watch the tachometer but I just know what I am looking for and know what is supposed to happen and for some reason the torque converter decides to take a break after a while. When the CHECK ENGINE light comes on every time this happens, the error is an OBD II code J1870 "Tranmission component slipping." I do all the PCM scans to the computer myself and that is the repeating code. I took the car on a trip this weekend and I had to clear my check engine MIL 5 times. J1870 everytime. I predicted the light coming on each time before it occured because I noticed the loss of overdrive in every case. Someone help me. Is my torque converter clutch (TCC) solenoid messing up?? Fluids are fine, that is the first thing I ALWAYS check. Where is that solenoid, in the valve body? What could this be? Should I drop the trans pan and drain the fluid and refill it and try that? I drove the car 70 miles home from a friend's place tonight and it had screwed up all day, she was fine the whole way home. I could not get it to mess up. Could this problem, whatever it is, be correlated to how many times I knock the torque converter in and out of locked/unlocked status with the gas pedal? For example, letting it slip into locked status for highway cruising, you are not going to get the TCC Solenoid hot because you are keeping it locked whereas, if I was punching the gas every minute and jumping into passing gear back and forth, then I am constantly putting the transmission in a position where it needs to re-lock with the torque converter, thus causing something to heat up. This seems electrical to me, I know that some things that are electrical start messing up when they are hot. Please advise me. Thank you so much.

posted by  cmeseadoin

First... please use paragraphs... phew....

Second, I would consider myself less capable in car repairs that you seem to be. If the computer is telling you its slipping, and its obvious it an error code, somethings defintely afoul. Therefore, I would suggest you take it down to the Chevy dealer, tell them "My torque converter is not locking. Please have it fixed. Don't charge me for inspecting it, just fix it.".

And obviously since you have worked on cars professionally, you know that one Chevy dealer may or may not charge for repairs as expensively as the dealer down the street.

My final thought: Follow one of the dealer mechanics until he goes into a bar. Come in shortly later, start up some idle converstaion, play a game of pool, buy him a drink, and then ask his opinion. Hell, he may even help you fix it for quite less than it would cost incurring shop charges.

posted by  Nemaroller


Thank for the advice! I appreciate the suggestions regarding paragraph format, unfortunately my description was in fact exactly that.....a detailed description of the problem from start to finish. It was not a "separate thought" or a different topic, therefore, I think my english teach probably would have not been too harsh on me for the format that I chose.

I certain did enjoy all of your "technical" advise on the situation, particularly the part about "following a mechanic to a bar" and trying to get him to repair my gearbox for less $. Gee, I think I placed this add and did so with very intense technical information and I was looking, at the time, for a very technical answer from someone that may know what they are talking about. I certainly was not looking for an english grammar lesson or anything like that....that won't fix my car and certainly guarantees itself to be a waste of my time.

I placed this posting back on the 1st of June and have already fixed this problem as of about one and a half months ago or so. I took the transmission out and rebuilt it. That cleared it right up. TCC Solenoid and lockup torque converter as well as all seals and internals. That was my feeling all along and I posted on here to get backup that I was right from someone technical. Thanks again for humoring me, however, people that post on here are normally looking for technical answer and not bullshit ones. Thanks!

P.S. Like the paragraphs here? See, this had separate thoughts in it so, therefore, as per english class I used paragraphs. Perhaps you should direct your interests away from things that you have NO clue about ( IE cars ) and place your bid on something like teaching english! Just a suggestion from someone ( me ) that DOES know cars...and english. I am sure there are plenty of chat rooms where you can sit an analyze sentence structure all day, so please leave car analysis to those of us with worthwhile posting on this web site.

posted by  cmeseadoin

oh and Nemaroller, one more thing I forgot to mention. Why is there so much emphasis on getting this thing to the Chevy dealer? From my detailed description, one would think that I may be looking for info on how to do this myself....wouldn't one? If all you can suggest on a technical website, where someone knowing as much about cars as you can glean from my posting that I do, is to take it to the dealer.....you CERTAINLY need another hobby. Good luck with persuing your english goals.

posted by  cmeseadoin

Wow! That should generate some nastygrams. ;)

posted by  vwhobo


The bottom of my posts says it all......"I hate stupid people...die, die, die!" :-) That asshole waisted my time basically so I wanted to "let him know." Later :-)

posted by  cmeseadoin

Well, I must say I'm glad you figured out your car problem.

Yes, I don't know much about transmissions. Never tore one apart, probably never will. Too much hassle-- and from people I know that have-- they almost always seem to have problems with it down the road. Besides, I'm not a certified mechanic, so I doubt my lender nor my insurance company would look favorably on me tinkering with a car still under payment.

The whole major point of my post was to help you find help. NOBODY likes to read a full page of text jammed together, so someone with the expertise would most likely tire of reading your post and move on.

By the way, I'm no english major, but for christ sake, your first post did contain seperate points. You don't have to switch between talking about your car's transmission to talking about the president to necessitate a new paragraph.

As far as your other problems, I can't help you... (stupid people like ones who waste their time to post 2 more times to lash out at someone, because they were TOO busy to read a 100 word reply).

Myself, I don't work on new vehicles much. But I do help mechanics and engineers... like this thread helping a jet engine mechanic devise software to interpolate correct torque settings given altitude and temperature... http://www.vbforums.com/showthread.php?s=&threadid=198841&highlight=altitud e

posted by  Nemaroller

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