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

The body control module (BCM) monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the engine control module (ECM) via the GMLAN serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired vehicle speed. The ECM uses the throttle actuator control (TAC) motor in order to maintain the vehicle speed. For further review of the TAC System, refer to Throttle Actuator Control (TAC) System Description .

Ignition voltage is supplied to the cruise control switch from the 2-ampere CRUISE SW fuse located in the integrated BCM fuse block. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM detects a specific voltage value that is associated with any cruise control function switch being activated. When the normally open cruise control on/off switch is turned ON, the switch closes and the BCM detects a predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the on/off switch is active. Similarly, when the + RES switch or the - SET switch are pressed, the BCM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. 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 switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a GMLAN serial data message to the BCM. The BCM then sends a class 2 serial data message to the head-up display (HUD) in order to illuminate the Cruise Speed SET XXX message. The - SET switch or the + RES switch will remain inactive when the BCM has not received the predetermined voltage signal from the On/Off switch. Pressing the accelerator pedal, while the Cruise Control System is engaged, will allow 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 switch and the + RES switch. When the Cruise Control System is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the - SET 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 switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the - SET is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing and holding the + RES 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 + RES 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 + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily pressing the + RES switch after the Cruise Control System has been disengaged by pressing the brake pedal, will recall the previous set vehicle speed that is recorded in the ECM.

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

The BPP sensor is mounted on the brake pedal bracket. Pressing the brake pedal while the cruise control is engaged will disengage the Cruise Control System. The body control module (BCM) monitors the BPP sensor via the brake pedal position sensor signal circuit. The BCM sends a GMLAN serial data message to the ECM and to the transmission control module (TCM) indicating the position of the brake pedal. For further information on the BPP sensor, refer to Exterior Lighting Systems Description and Operation or to Brake Pedal Position Sensor Calibration . When the clutch pedal is applied, the normally opened CPP switch closes and the ECM detects a high signal voltage on the CPP switch signal circuit.

The Cruise Control System will also disengage when the cruise control On/Off switch is switched OFF or 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 GMLAN serial message to the BCM. The BCM then sends a class 2 serial data message to the HUD in order to turn OFF the Cruise Speed SET XXX message.

The vehicle speed stored in the memory of the ECM will be erased when the cruise control on/off button is turned OFF, or the ignition switch is turned OFF.

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