bsmith3163

Getting my 81 back on the road after an extended (15 year) sit. Car was running great for about an hour. As I was pulling into my driveway (at slow speed) the car stalled. Put it in park and it started right up, shifted into drive and the car stalled again. It will shift into park, neutral and reverse just fine but as soon as you put it into drive, 1, 2 or 3 it stalls. The *** end of my vette squats when I put it into drive, so I know that it is putting torque to the transmission. Let it sit for a couple of hours and it went into drive just fine. I think that the lockup torque converter is locking up at the wrong time. I understand that there is an electrical connection to the transmission that controls the lockup function. Where is that connection? Driver's side? Passenger's side? I can not find any reference to it at all. Any help is appreciated. Any pictures showing me what exactly to unplug is appreciated even more. Thanks

StDomingos

TC lockup on the '81 is controlled by the computer. I'd bet that the majority of '81 owners no longer have the computer present or functional. If you are still one of those rare folks with a fully functional Engine Control Computer then there will be a square 4 pin connector on the TH350c transmission just above the transmission pan. Disconnect this plug and there goes your lockup.

You won't damage the 350c by running it without the lockup by the way, your highway fuel mileage will just be worse.

centralcalvette

Stdomingos is absolutely right. You probably won't notice the mileage difference.

'75

If it still has the issue after the plug is disconnected, then you will need to remove the trans pan and replace the LU solenoid.

DaveL82

My 80 had the same problem with it's turbo 350C trans. While mine was not computer controlled, it operated in a similar way. There's a solenoid in the valve body and I tried disconnecting the wire that powers the solenoid and this didn't help. I found the solenoid valve port was getting clogged which builds pressure even when not activated. My solution was to remove the solenoid from the valve body so it operated as a non C type trans. I put 20K miles on the trans after removing the solenoid with no issues except the trans couldn't go into lockup mode.

2airtime2

My '80 th350 didn't have any electrical plugs on it but I had a (green I believe) wire under the hood label (by previous owner) tc lockup. I have put a 700r4 in it now and have the plug which I will wire 12v to thru a 212331 vacuum switch.


If you'd like to retain lockup without the computer I believe you could wire your th350 like I'm doing my 700r4???