P0720

The OBD II code Torque converter circuit stuck open. This has happoned a couple of times. I took the car to a shop and after checking out I was told that everything was working fine and if I could live with the light (service engin soon) being on, drive it ! On the way home the service engin light went off, but today (10 days)The light come on again. Same problem. Care runs fine except at a stop sign the shift hesitates a couple of times while shifting. I heard that there is a multiwire plug that hooks to the transmission that might not be making good contact.. Where is this plug and can it be cleaned? Contact cleaner? Thanks ernie