Cruise Control

CRUISE CONTROL
The Powertrain Control Module (PCM) controls vehicle speed by operation of the speed control servo vacuum and vent solenoids. Energizing the vacuum solenoid applies vacuum to the servo to increase throttle position. Operation of the vent solenoid slowly releases the vacuum allowing throttle position to decrease. A special dump solenoid allows immediate release of throttle position caused by braking, cruise control turn off, or ignition key off.

The speed control electronic control circuitry is integrated into the Powertrain Control Module (PCM). The PCM speed control functions are monitored by the On-Board Diagnostics (OBD). All OBD sensed systems are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain failures it detects. See On-Board Diagnostic Test For Powertrain Management/Computer and Control System/Vehicle Speed Control System for more information. The PCM cannot be repaired and must be replaced if faulty.