Cruise Control: Description and Operation

The cruise control system uses mechanical and electrical devices to maintain the car's speed at a setting selected by the driver.

System Description
The Engine Control Module (ECM) receives command signals from the cruise control main switch and the cruise control Set/Resume switch. With the ignition switch in ON (II) or START (III), voltage is provided to the cruise control main switch through fuse 5. When you push the switch to ON, power is provided to the engine control module (ECM) and the brake switch.

The engine control module (ECM) receives information about operating conditions from the brake switch, the Vehicle Speed Sensor (VSS), the clutch switch (manual transmission) or the A/T gear position switch (automatic transmission). The engine control module (ECM) then sends signals to the throttle body control motor which regulates the throttle position to maintain the selected speed. The engine control module (ECM) compares the actual speed of the car to the selected speed and uses the result to determine whether to open or close the throttle.

The brake switch releases the system's control of the throttle at the instant you press ON the brake pedal. The switch sends a signal to the engine control module (ECM) by removing power from the normally closed brake input (GRY wire) and providing power at the normally open brake input (GRN/WHT wire). The engine control module (ECM) responds by allowing the throttle to close. The clutch switch (Manual transmission) or the A/T gear position switch (automatic transmission) sends a "disengage" signal to the engine control module (ECM) that also allows the throttle to close.

The cruise control system will set and automatically maintain any speed above 30 mph (45 km/h). To set it, make sure that the main switch is ON, and the indicator light is ON. After reaching the desired speed, press the SET switch. This sends a "set" signal to the cruise control unit which, in turn, controls the cruise control actuator to maintain the set speed.

When you push the SET switch and the cruise control main switch is ON, the "cruise control ON" indicator light comes ON.

You can cancel the cruise control system by turning the main switch OFF. This removes power to the control module and erases the set speed from memory. If the system is disengaged temporarily by the brake switch, clutch switch, or A/T gear position switch, and the car speed is still above 30 mph, press the RESUME switch: the car will automatically return to the previously set speed.

For gradual acceleration without pressing the accelerator pedal, push the RESUME switch and hold it there. This will send an "acceleration" signal to the control unit. When you release the switch, the system will be reprogrammed for the new speed. To slow the car down, press the SET switch in and hold it there. This sends a "deceleration" signal to the control module, causing the car to coast. When the desired speed is reached, release the SET switch. This reprograms the system for the new speed.