[Bigdav160]

In '88 the TCC was computer controlled. On the transmission there is a power supply from a NC brake switch, ground from the computer to control the TCC solenoid and there is a wire from the 4th gear pressure switch to tell the computer when you are in high gear.

You can home brew your own setup or buy a kit from a vendor. On a really light weight vehicle you might get away without hooking it up but on something like a truck it needs to be working to keep the fluid from overheating