Cruise Control: Description and Operation

The Electronic Cruise Control System is used on all Cadillac models except Cimarron and utilizes either manifold vacuum or a vacuum pump to activate the throttle power unit or servo. Throttle position is changed when the servo unit diaphragm receives varying levels of vacuum, controlled by a solenoid valve. The solenoid valve modulates the vacuum signal to the servo in response to commands from the electronic controller. The electronic controller monitors signals from the engagement and instrument panel switches, electric brake release switch, and the speed sensor. The speed sensor, located at the rear of the speedometer cluster, signals vehicle speed to the controller. These signals are used by the controller to activate the solenoid valve, regulating the level of vacuum to the servo diaphragm. This system uses two brake release switches. An electric brake release, mounted on the brake pedal support, turns the system ``Off'' and vents the servo diaphragm to the atmosphere through the solenoid valve. A second brake release switch, a vacuum release valve also located on the brake pedal support, vents the servo unit to the atmosphere.