1987 Transmision lock solenoid

In reference to my earlier post 1987 Century with Issues:

Hi guys!

Some of you identified the sensor on the lower right of the engine/transmision as the transmision lock solenoiod. I checked and I've got the four speed. So not fixing this will waste it over time? Ok. What mechanically does this thing do and how do i replace it? I looked in my Haynes manual but couldn't find it. Does anyone know if it's there?

Thanks for the help! I fixed the other stuff and now the engine runs great! For about a week the engine would occasionally stall when you put it in reverse or when it was in idle on a hill, but after driving it for a while it works fine. Maybe the computer needed time to relearn how to run the engine?

-Ben

The solenoid in question locks up the torque converter so the engine is directly attached to the wheels (no slippage in tranny). You may unplug the torque converter clutch sloenoid but you will lose a little gas mileage. You may hear that this will cause damage. I can only say that I am a long term GM owner and have one that has been unpluged for 3 years without effect. The part cost about $40 here in Florida. It is a bit of a job to change. You must remove the cover on the driver side of the tranny. Haynes prints a really helpful book on GM trannys about $15 anywhere. But I still have one that is unplugged :-)

if its the 4spd (440T4/4T60) you CANNOT unplug that and expect the tranny to live. You may only do the unplug trick on the 125C/3T40

Thanks Quaddriver, I came to assist and received info myself. The one I have unpluged is the 125C. But I also own a 4T60 that I will have to be more carefull with. The 4T60 also appears to have a lot more wires on the same plug. Thanks again.