I just bought a 1997 Z28 on the cheap, its salvage title from a transmission theft.

The previous owner and a "friend" mechanic of his put the current transmission in. Its obviously NOT the correct transmission from a '97 (he swears it is), but it all connects up fine except for the TCC slip monitoring wires which have no place to go. The metal tag with the part number that should be riveted on the side has been removed, so I have no idea where or what this transmission came from. My best guess is a pre-OBD-II Camaro where slip monitoring wouldn't really have been needed. These wires not being connected turn on the MIL with code P1860, I've reflashed it so this code doesn't come on anymore.

This transmission has been fun, since the transmission mount was broken when I got the car, and I've just replaced it again not even a month later because it ripped in half. Hopefully this polyurethane one won't break again so easily (also did the engine mounts this time). Not really the point of my post though...

You can feel the TCC lock up, it locks early (10 MPH) and only unlocks when I manually change gears using the gear selector lever. It doesn't unlock when I come to a stop either, it runs the car down to 4 or 500 RPM on the tach (which I've heard is roughly 200 RPM high), and finally feels like it just takes it out of gear (or unlocks the converter, I can't tell which). I've had it die a few mornings when it was a little colder out. It doesn't always stay locked either, its not a problem at every stop sign. It is a problem at a good 1/3+ of my stops.

Anyone have any ideas as to what would cause this and what is the cheapest way to go about fixing it?

 

The wiring that comes from the transmission carries the tcc wires. You dont have to have the exact same transmission that came out of the car. 700's or 4l60's are in many many gm vehicles. I dont understand how you know that the tcc wires arent connected?? A torque converter shouldnt lock up until 3rd and 4th gear in a 4l60. This really sounds like a bad ecm problem! You need to get a scanner on it and see if the computer is calling for it to lock up. Temperature, speed, gear, and TPS determine when to lock up a converter. If this is not the case then there is a pulse valve in the valve body that could be sticky. Also there is a valve in the pump that could cause this... If this problem is becuase of the wrong tranny then it could just be a hydraulic 700. If this is the case then a 4th gear switch needs to be wired up. If the mechanic wired up a 4th gear switch then me put it on the wrong pressure switch. It needs to be connected to an open switch. If no open switch is there then you need to replace it with one. Let me know some more about your problem!

 

The P1860 code (I think thats what it was) is turned on when the voltage from some TCC related wire was much too high, or much too low, for more than 5 seconds. I took it to a mechanic to troubleshoot this code, and he called me a few hours later saying that the 2 wires for slip monitoring weren't connected to anything, but all of the other connectors and wires were all hooked up fine. I reflashed it to remove the code and he didn't think it would really be a problem, since it appears to be an older transmission that didn't monitor slip anyways. I also went down and looked at these 2 wires before they took it down off the ramps, but I don't remember what color the were or much about them. There were no place on the trans to plug them in, he showed me where they *should* have gone into the trans.

As far as I know, they took this transmission and put it straight in without any kind of switches or anything else wiring related. I'll get a scantool on it on the drive home tonight and see what its doing.

A relative of mine is wondering if maybe it is just leaving it locked because it isn't detecting any slip? Would the ECM really do this in 4th gear at such a low RPM? It happens if I put it in Drive for 3rd gear as well, but I haven't tried 2nd.

I'm in the OBD-II scantool business so I know a fair deal about cars, but I don't know all that much about transmissions (only 19, not enough time to know everything ). Is an automatic always in gear? If the converter is fully locked and I come to a stop will it die or put it in neutral (meaning its not always in gear)?

If I move the gear selector lever from OD to D, it feels like it unlocks the converter. Many times it feels like it locks up again after 2 or 3 seconds. I thought I'd read somewhere that it should always unlock the converter when you press the brake pedal.

 

I was hoping that it was just the transmission mount being completely in half, and something was binding up. Had the mount replaced today and it had this problem on the drive back.

I guess this is what I get for being poor and getting a Camaro for $2k...