Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.

The following are the main components of the cruise control system:

The engine control module (ECM) monitors the cruise control switch signal circuit in order to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed sensor signal circuit in order to determine the vehicle speed. The ECM uses the throttle actuator control (TAC) motor in order control the vehicle speed. For further information on the TAC system, refer to Throttle Actuator Control (TAC) System Description for the 3.9L engine, or Throttle Actuator Control (TAC) System Description for the 5.3L engine. Ignition voltage is supplied to the cruise control switch from the 10 ampere CRUISE fuse via the ignition 1 voltage circuit. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The ECM detects a specific voltage value that is associated with the cruise control function switch being activated. When the normally open cruise control ON/OFF switch is turned ON, the switch closes and the ECM detects a predetermined voltage signal on the cruise control switch signal circuit indicating the switch is ON. Similarly, when the normally open RESUME/ACCEL switch or the normally open SET/COAST switch are pressed, the switch closes and the ECM detects the predetermined voltage signal on the cruise control resume/accel and set/coast switch signal circuit. The RESUME/ACCEL switch or the SET/COAST switch will remain inactive when the ECM has not received the predetermined voltage signal from the on/off switch.

The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following cruise control switches:

To engage the Cruise Control System, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise ON/OFF switch ON and momentarily press the SET/COAST switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a class 2 serial data message to the instrument panel cluster (IPC) in order to illuminate the Cruise Engaged indicator in the IPC.

Pressing the accelerator pedal while the Cruise Control System is engaged, allows the driver to override the Cruise Control System in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the SET/COAST switch and the RESUME/ACCEL switch. When the Cruise Control System is engaged, pressing and holding the SET/COAST switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the SET/COAST switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing the SET/COAST switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the SET/COAST is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph).

Pressing and holding the RESUME/ACCEL switch, when the Cruise Control System is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the RESUME/ACCEL switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing the RESUME/ACCEL switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the RESUME/ACCEL switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the RESUME/ACCEL switch will recall the previous vehicle speed, after the cruise control system is disengaged by pressing the brake pedal.

The powertrain control module (PCM) disengages the cruise control operation based on the signals from the following switches:

The Cruise Control System will disengage when the brake pedal is applied. When the brake pedal is applied, the normally closed TCC brake/cruise release switch opens and the normally open stop lamp switch closes. The ECM detects a low signal voltage on the TCC brake/cruise release switch signal circuit and a high signal voltage on the stop lamp switch signal circuit. When both signals indicate the brake pedal is applied, the ECM will disengage the cruise control system. Pressing the clutch pedal while the cruise control is engaged will also disengage the Cruise Control System. The engine control module (ECM) monitors the CPP sensor via the CPP sensor signal circuit as the voltage signal decreases while the pedal reaches the fully applied position.

The Cruise Control System will also disengage when the cruise control ON/OFF switch is switched OFF. The engine control module (ECM) determines when the cruise control ON/OFF switch is activated. The vehicle speed stored in the memory of the engine control module will be erased when the cruise control On/Off switch is turned OFF, or the ignition switch is turned OFF. The Cruise Control System will also disengage when the ECM detects that a driver override function has been active for approximately 60 seconds. When the Cruise Control System has been disengaged, the ECM sends a class 2 serial message to the instrument panel cluster (IPC) in order to turn OFF the Cruise Engaged indicator.

Each time the Cruise Control System is disengaged, the ECM will keep track of the reason for system disengagement. The last 8 disengagement reasons will be recorded within the ECM memory, and can be viewed with a scan tool.

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist: