Chevy Transmission revisited

I have a 1999 Chevy Lumina car. The trans is shifting weird. Sometimes it seems to short shift. Other times it shifts really hard. And other times it seems to not down shift all the way to first gear?? Sometimes it drives normal. The check engine light comes on. The code is P0742. I had it checked out and they said it was a TCC switch. I took it to my mechanic here in town and he said it was more of a mechanical problem, other than being that switch. ( perhaps a sticking valve in the valve body ) He flushed and refilled the trans with new fluid. It’s still doing the same thing.

This problem is random. I don’t know if it means anything but, when I first drive the car, it shifts great. Then it will screw up and the light comes on. Sometimes it will go away after I stop somewhere like a store. The light stays on but it doesn’t shift bad. Other times once it starts, the problem doesn’t go away.

Thanks for any ideas on this matter


This is the problem with automatic transmissions…repairing them is nigh impossible.

I had shifting problems with my 1992 Ford Tempo. After talking to a bunch of people, (shops, friends, junkyards, internet forums etc) I learned that the governor gear can be replaced relatively easily. If that’s been replaced and that doesn’t solve the problem, (and it’s not the electric switch) than you probably will have to get a new transmission or rebuild your current one.

Everything is inside the little black box…and inaccessible, until the mechanic spends half a day removing the transmission from the car and putting it back together which all told will take at least a day…

Since transmission rebuilds run into the thousands of dollars I would recommend replacing the governor gear first…that’s what fixed my problem.

The torque converter clutch (TCC) switch (or solenoid, one and the same), can cause the symptoms you are describing. Since it is an electrical component, it is much more likely to cause an intermittent problem than any mechanical part. I have a Buick that had the TCCS go bad in it, and the symptoms were as follows: premature or inappropriate locking of the torque converter clutch (which creates the sensation of hard shifting or short shifting to someone without the specific experience to know the difference) and the torque converter failing to unlock on deceleration or stopping the car, resulting in shuddering, then stalling, like leaving a manual transmission in gear with the clutch released and coming to a stop. You may want to consider replacing the TCCS before you condemn the car. Mine only cost about $20-30 for the solenoid, $15 for a side cover gasket, five quarts of trans fluid, and a couple hour’s work.

Thanks for the info. Mine hasn’t stalled yet but it does sometimes seem like it shutters while turning into a parking lot or something like that. How hard was it to get to the switch? Is the switch inside the trans?? or is it on the outside like an old vaccuum modulator? The mechanic in town here said he would have to remove a cross member to get it. I think he said it would be almost $700 for the whole job. Is there anywhere I can go to see a drawing of what it looks like or where it is on the trans ?

Thanks for any help in advance


There are several known issues which would cause this code depending on which trans you have. Basicly the 0742 code is set when the TCC release switch is closed when the computer is commanding it off. One reason could be a pressure regulator problem causing the line pressure to fluctuate rapidly setting the code. Sealing rings on the turbine shaft which have worn out and have come apart would also affect the line pressure. One more thing, and I’m going to have to look this up to be sure I am thinking about the right transmission. There was a TSB out on failure of the drive sprocket support bearing. This was causing problems with the earlier transmissions and I think it was setting the 0742 code. When I think about it, I can see it causing an 0742 I’ll look up that TSB to be sure on Tuesday. I’d like to know what trans you have. Which motor do you have in the Lumina???


My Lumina has the 3.8 L As far as the trans I’m clueless… sorry