Cruise Control Servo: Description and Operation

SYSTEM OPERATION
The servo unit consists of a solenoid valve body, and a vacuum chamber. The PCM controls the solenoid valve body. The solenoid valve body controls the application and release of vacuum to the diaphragm of the vacuum servo. The servo unit cannot be repaired and is serviced only as a complete assembly.

SPEED CONTROL SERVOS-PCM OUTPUT
The PCM controls the speed control vacuum servo. The PCM supplies power, through the brake switch, to the servo. Based on the speed control switch inputs to the PCM and the speed control strategy, the PCM provides ground to the servo vacuum or vent circuit as required. When the PCM supplies a ground to the servo vacuum circuit, the speed control system opens the throttle plate to obtain or maintain the selected road speed. When the PCM supplies a ground to the servo vent circuit, the speed control system releases the throttle plate.