Circuit Operation

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. The electronic cruise control system has the capability to cruise, coast, resume speed, accelerate, and tap-up and tap-down. (Note: Steep grades up or down may cause variations in the selected speeds.)

Cruise Control Module
An electronic controller and electric motor are contained in the cruise control module. The controller monitors vehicle speed and operates the electric motor. In response to the controller, the motor moves a connecting strap that is attached to the cruise control cable. The cable moves the throttle linkage to vary throttle position in order to maintain the desired cruise speed. The cruise control module contains a low speed limit which prevents system engagement below a minimum speed of approximately 25 mph. The module is controlled by switches located on the multi-function lever. Cruise control is in Standby Disabled mode until all conditions inconsistent with cruise control operation are cleared.

With the ignition switch in RUN, battery voltage is applied on CKT 1141 to terminal F of the cruise control module. When the cruise ON/OFF slider switch is moved to the ON position, battery voltage is applied on CKT 397 to terminal A of the cruise control module connector. If the brake pedal is not depressed, battery voltage is present on CKT 420 at module terminal D. If the brake pedal is depressed, battery voltage is present on CKT 17 (Buick/Oldsmobile) or CKT 20 (Pontiac) at module terminal G. Terminal G must have current for cruise control to operate (disable) properly.

When the slider switch is moved to the R/A position, battery voltage is applied on CKT 87 to terminal C of the module. With the SET/COAST switch depressed, battery voltage is present on CKT 84 at module terminal B. Cruise control module connector terminal K (CKT 817) is the vehicle speed signal terminal. In operation, vehicle speed signal voltage oscillates between a high of battery voltage and a low of 0.5 volts. Ground (CKT 1150) is at module terminal E. The cruise control module uses terminal J (CKT 85) to signal the Powertrain Control Module (PCM) that cruise control is engaged. The PCM then determines the correct shift pattern for the transmission. The PCM uses terminal H (CKT 83) to inhibit cruise control operation when conditions not consistent with cruise operation are present. The conditions are listed under Troubleshooting Hints. Troubleshooting Hints