GM Service Manual Online
For 1990-2009 cars only

The Throttle Actuator Control (TAC) Module, receives inputs from the Powertrain Control Module (PCM), through the TAC serial data circuits, and from driver controlled inputs. The cruise control ON/OFF switch is supplied battery positive voltage through circuit 1239 from the CR CONT fuse #20 in the instrument panel electrical center. When the cruise control ON/OFF switch is in the ON position a 12 volt signal is supplied to the TAC module through the cruise on/off signal circuit 397. The cruise control SET and R/A switches are supplied voltage through the cruise control ON/OFF switch when in the ON position. When the SET switch is pressed while the ON/OFF switch is in the ON position a 12 volt signal is supplied to the TAC module through the cruise set/coast signal circuit 84. When the R/A switch is pressed a 12 volt signal is supplied to the TAC module through the resume/accel signal circuit 87.