Cruise Control Servo: Description and Operation

PURPOSE
The speed control servo is used obtain and maintain a selected road speed.

CONSTRUCTION
The speed control servo houses the throttle actuator, speed control vacuum solenoid, and speed control vent solenoid.

OPERATION
The Powertrain Control Module (PCM) operates the speed control vacuum and vent solenoids, by switching the ground path on and off. Power to the solenoids is supplied by the speed control relay.

When the PCM grounds vacuum solenoid, the speed control system opens the throttle to obtain a selected road speed.

When the PCM grounds vent solenoid, the speed control system closes the throttle to reduce road speed.

The PCM balances the two solenoids to maintain a selected road speed.

CIRCUIT OPERATION
The vehicle speed control servo is supplied power from the stop lamp switch on circuit V30.

Circuits V36 and V35 are connected from the servo to the Powertrain Control Module (PCM). These circuits are used to control the vacuum and vent of the servo.

Circuit V36 is used for the VACUUM, and circuit V35 is used for the VENT.

Circuit V35 connects to cavity 53 of the PCM connector, and circuit V36 connects to cavity 33 or the PCM connector.

Ground for the vehicle speed control servo is provided on circuit Z1. The Z1 circuit terminates at the left front frame rail.