2000 P0742 OBDII code Toque Converter Clutch

[pjw73nh]

This post is a continuation of my original post. http://www.automotiveforums.com/vbul....php?t=1016652
I reposted it with a more descriptive title:


Updated info:

130k miles.

I am truly hoping that you wizards out there will tell me there is still more that I can try and that I don't need a new tranny. But I am not holding out much hope based on other threads I have read. I just spent about $1500 in parts and dozens of hours of my own labor this spring to get this car to a point where it was running perfectly, needed nothing and would last me at least another 2-3 years. Now I get THIS thrown at me !!!!!!!!!

Vehicle is back home. I had it scanned, confirmed the previous diagnosis: P0742 TCC / brake switch stays high.
Here are some more symptoms / observations / tests I have done since I am home now.

1. SES light is out (it was reset /cleared yesterday after the scan. The P0742 was the ONLY code set.

2. The transmission shifts beautifully through all gears, all of the time. The trans fluid is reasonably fresh, is bright red, and has no odor of burning whatsoever.

3. Driving it to work today, when TCC locks up (I presume a few seconds after getting into 4th, and not under much load) there is a noticeable "lurch / stiff shift" when it locks up. Not smooth the way it used to be. This only happens during lockup. The rest of the shifting is very smooth.

4. When the trans was functioning normally I used to be able to purposefully get the TCC to unlock by accelerating slightly and stepping on the brake to activate the switch. You would be able to hear the engine rev slightly higher when you stepped on the brake to "unlock" it. It does not do this now. There is NO CHANGE in the engine speed when I do this.

5. That said, if I drop the shift lever out of drive and into "3", (I realize that the TCC won't lock up in "3"), and then do the same test as in #4 above, I DO hear the engine rev (I presume from a slight downshift) when I step on the brake. Thus, I believe this proves the brake switch is good. Doesn't this also tell me that the TCC and solenoid are working ok as I can "manually" get it to disengage by shifting to "3" ?

What else can I do to further isolate this issue?

I found this on the internet: http://autorepair.about.com/cs/troub.../aa061701a.htm

It appears to be a good troubleshooting aid, but I can't tell if it actually applies to the Venture Transmission. It only says "GM". Any thoughts?

Does my issue sound like it is (for certain) the TCC solenoid? Or could it be external? I hate the thought of a new transmission. This one works great except for this new issue. I have always maintained the vehicle very well and never abused it. I have had it since new.

I saw where one person tried some Seafoam for a hundred miles or so, and then had a full trans flush and said he had good success? Is this worth a try ? Or am I just going to add on another $100 cost for what is inevitably going to be a "new transmission"?.

Thanks for all your help.

[pjw73nh]

Update:

I have driven the van for about 1000 miles since this first happened. There are no DTCs that my scanner (EQUUS 3160) detects set since the last time it was reset (30 days and 1k miles ago). Stepping on the brake DOES disengage the TCC.

The only symptom I have now is that when the TCC locks up, I feel a slight lurch as it engages. No sounds other than the engine rpm's loading down. Other than that the trans shifts, sounds and smells great. Nothing out of the ordinary. I am wondering if this may be a motor mount type of problem or something else.

Thoughts?

Thanks...

[lesterl]

The TCC does engage in 3rd and 4th.

Might try a new Modulator? Front side of transmission.... IDK if a 2000 has a Vacume one or not.... IDR what years....

[lesterl]

Well, looking at the parts list looks like a 2000 doesnt have a modulator as such..... Maybe a can of TransX or TransMedic or something...... You might have a speck of dirt in a solenoid or something. I wouldnt do a backflush on the trans, good way to drive more dirt into the solenoids.

[pjw73nh]

Thanks for the replies folks. Well here it is almost 2000 miles after the initial incident/DTC set, and I just experienced it myself. The last time it happened my son had the car.

It was just like he mentioned. TCC was stuck on. I could get it off by moving the selector to any position. It set the MIL. It behaved like this until I shut the car off for about 10 mins (my time in the bank), MIL still on, but shifted and performed fine as if it had never happened for the rest of the trip home (a few miles).

I got out my trusty scanner and found another P0742 DTC. Only one. It also gave me some freeze frame data of some of the engine parameters at the time of the dtc set.

I am confused about what the code actually means. I see "TCC solenoid circuit stuck on" (from the scanner). GM shop manual says "TCC Stuck on". Could this be an electrical problem (IE the "circuit" reference, or are they using circuit as in a "plumbing" circuit") and not a mechanical issue.

It's only happened twice in about 3000 miles or so.

Just thinking out loud....

P.../NH

[lesterl]

Could be a fluid path issue.....

[pjw73nh]

Update #2:

Been using the car as is since the issue first arose.

I have done nothing except make sure the fluid is clean, and up to level. I think it may be a little OVER level. Could this cause this issue?

The fluid is clean, no particulates in it, and smells fresh. No odor of any kind.

Given the age and mileage of the veh, I am going to just live with it until it no longer drives. It appears that it only affects the lock-up of the TC. My only concern is being stranded where the car won't even drive. This doesn't seem to be the kind of issue to do that.

There are a few more symptoms I owuld like to leave for anyone who would like to comment.

The problem is VERY intermittent. It is unrelated to miles driven, ambient or operating temperature, or time. It just happens, usually when at cruise speeds between 45 and 60 mph. With no perceptable symptoms, the MIL comes on. Then when I come to a red light or stop, the TC doesn't release until I manually shift the selector into neutral. Then I go back in drive, and it is fine for a few weeks etc.

The MIL stays on for anywhere from 1-3 trips after that, and then it goes out and it may not happen for another 2-3-4 weeks. Each time it sets a P0742.

Just during regular driving (not when the issue is happening but all the time while driving) I noticed is that when I start from a stop, It shifts from 1-2 at the correct point, then from 2-3 it shift at the right point, but IMMEDIATELY either goes to 4th, or to TC lockup. I can't really tell.

I was thinking that because I drive like an old fart, the trans has adapted to my way of driving. What's the best way to reset the adaptive pattern in the trans (short of taking it to a dealer)?

Thoughts comments welcome..

[robertccach]

I get the same code except my 2000 venture wont engage in any gear what so ever!!!I dropped the pan and put in new filter and fluid ect and it did not help.Also I noticed when I run the van the fluid level does not drop and it does not even seem to heat up at all...Any thoughts about this?Please,anything would be helpfull....thanks

[pjw73nh]

Originally Posted by robertccach

I get the same code except my 2000 venture wont engage in any gear what so ever!!!I dropped the pan and put in new filter and fluid ect and it did not help.Also I noticed when I run the van the fluid level does not drop and it does not even seem to heat up at all...Any thoughts about this?Please,anything would be helpfull....thanks

Could it be that the P0742 is "coincidental" with another failure? It sounds like there is a linkage issue. Does the selector actually feel like it is moving something? I am not sure whether this trans uses mechanical linkage, or an electrical selector switch. Either way, perhaps follow the linkage/wiring and see if the appropriate device on the trans is being actuated.

Other than that, I'm afraid I'm not going to be of much help.

P..../NH

[merc81]

Originally Posted by robertccach

Also I noticed when I run the van the fluid level does not drop and it does not even seem to heat up at all...Any thoughts about this?Please,anything would be helpfull....thanks

Not sure you would really see fluid drop any amount until after the drivetrain travelled a few feet. You could check to see if the pump was doing anything by pulling a transmission coolant line loose from the radiator while the van was running in park.

I'm afraid to tell you this sounds like the time to pull the tranny out for rebuild.

[pjw73nh]

Update: car now has 146k on it. No "significant" changes other than the issue occurs more frequently at higher ambient temps. Up to the last week or so, it would happen every 2-3 months. Lately we have had very hot Wx. Daily temps in the 90s. Fluid still smells fresh. Not using any. A definite skip/slip is noticed between 40 and 45 mph under load. I am starting to theink this may be electrical related and me be fixed with a new or reprogrammed TCM. Maybe it's just a loose connection. Can anyone guide me to the TCM connection? I'd like to re-seat it.

Thanks...

[lesterl]

Worn Valvebody, good luck.....