TCC - Circuit Stuck On

Hey everyone! Just joined the forums today and hope I can get some help!

I have a strange problem you might be able to help me with! I have a 1999 Chevy Venture van with a 3.4l v6 in it, and am having a strange what seems to be either an electrical or transmission problem which I can explain pretty easily.

95% of the time after the van has been driven for 30 minutes and warmed up, I notice a strange chugging when it shifts from 1st to 2nd. The chugging gets less noticeable when it shifts into the higher gears. 2nd to 3rd, 3rd to 4th etc...

This is the strange part. If you put the vehicle in park and shut it off, and then restart it after it sits for 10 seconds or so the chugging is gone. It shifts beautifully. Could this be a problem with the computer or is it some kind of sensor resetting??

The computer is giving me a P0742 code. Which is "Torque Concerter Clutch Solenoid - Circuit Stuck on". I also have a code for the Mass Air Flow Sensor and Catalyst Efficiency which I think is related to other things. Any help would be appreciated.

Not a tranny guy, someone, I'm sure , will be here soon...

This chugging you feel during shifts, might be harsh shifts caused by full line pressure commanded by the PCM, due to the P0742 being set.....

Shouldn't let these different codes start to add up....

A scan with a trans function scanner can confirm if the tcc is sticking, less than this may cause expensive guess work.

A scan with a trans function scanner can confirm if the tcc is sticking, less than this may cause expensive guess work.

Speaking of which, how to scan the transmission codes? It seems to me that they do not occure on the normal ODB-II scanner I use.

This year does not have a seperate TCM....so the code should be set in the PCM, and should be readable......

Regarding the catalyst efficiancy...you have a #3 oxygen sensor that bolts into the catalytic converter. So either that sensor is reading bad or the catalytic converter is bad. Yes this is guess work here, but I would replace the sensor first because that is the cheapest route. If that does not fix the problem I would change the converter.

as far as emissions/engine management goes...the 'Mass Air Flow' sensor, just replace it. It is rare that the computer gives a false reading or a "collateral" reading for this sensor as this is the 2nd sensor read by the computer. The first being either the 'crank shaft' or the 'cam shaft' position sensor.

The TCC being stuck ON is worse than it being stuck off. As
maxwedge advised...get a full scan...you cant perform the scan with the basic OBD II tool...You gotta spend the bucks at a tranny shop.

The TCC is locked on. This results in pretty much the same experience you might have with a clutch if you left it in gear when stopping or tried to start out in the wrong gear. The TCC locks on because the solenoid gets stuck. This isn't the end for the tranny, but you should plan on a rebuild sooner rather than later. I've gone through this with three vans, all '99s.
Do a search over on the Olds silhouette forum and the Pontiac transport, as well as here. You should find many, many posts from myself and many others detailing this issue as its pretty well known for the vans from '99 thru 2003. The other issues you mention are not related.
Change the up stream O2 sensor, and remove and disassemble the MAF sensor to clean it. These jobs are also described in older posts. The MAF is pricey--don't replace it unless its burned out, they are pretty easy to take apart and clean.
John

He never said how many miles there were on the vehicle, or if the fluid was ever changed, but would a sea foam for transmissions application, followed by a pan drop fluid/filter change do him any good here?

This was my -go-round with a p0742. Still haven;t fixed it. Too expensive at this point, it happens after a long drive in warm to hot weather. Not so much in cooler temps. car goes into :"limp" mode. Pull over, turn off, restart. All is well.

http://www.automotiveforums.com/vbulletin/showthread.php?t=1016843

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