Cruise Control Operation: Notes
The adaptive cruise control system functions much like a standard cruise control system. The adaptive cruise control system automatically adjusts the vehicle speed to maintain a set distance gap from the front of the vehicle and the vehicle in the same path of travel. When the adaptive cruise control system is on and is following a vehicle or a vehicle enters the same driving lane, a follow vehicle graphic is displayed in the message center.
The adaptive cruise control system does not function if the vehicle speed is below 20 km/h (12 mph). As the vehicle slows down during automatic braking, the adaptive cruise control system discontinues braking at 20 km/h (12 mph). At that speed, an audible alarm sounds and the automatic braking from the ABS module is released. The driver must take over the vehicle braking control.
The cruise control deactivator switch (which is integral to the BPP switch) is an additional safety feature. When the brake pedal is pressed, the cruise control system deactivator switch opens and removes the ground signal from the PCM input circuit, releasing the throttle and immediately deactivating the system.
The CCM monitors the yaw rate signal from the ABS module and compares it to the wheel speed and steering wheel angle signals. If the ABS module determines the yaw rate is invalid, the CCM disables the adaptive cruise control. The message center displays the message COLLISION WARNING MALFUNCTION and/or ADAPTIVE CRUISE MALFUNCTION.
The CCM monitors the environment in front of the vehicle while active. If the radar beam is obstructed by a buildup of snow, ice, rain or other debris, or the vehicle is driven in a desert environment with no other traffic for extended periods of time, the sensor will trigger an ADAPTIVE CRUISE NOT AVAILABLE SENSOR BLOCKED SEE MANUAL message and will disable the adaptive cruise control. The adaptive cruise control will resume once the obstruction is cleared and the radar is able to detect targets, or upon a key cycle.
If aftermarket equipment, such as a snow plow, is installed on the front of the vehicle, obstructing the radar, the adaptive cruise control may function erratically. The adaptive cruise control will need to be disengaged using the menu option, and the operator will only have non-adaptive cruise control functionality.
The ABS module estimates brake temperature by monitoring applied brake pressure over a period of time and sends a message to the CCM when the estimated temperature is above a given threshold. An alarm sounds and the adaptive cruise control system is deactivated until the estimated brake temperature returns to cooler operating conditions. This condition can happen in a hilly or mountainous driving terrain. While the vehicle is hauling a heavy trailer with the tow haul mode OFF, the brakes can overheat more easily on long descents, which will disable the system.
When tow/haul mode is selected while the vehicle is operating in adaptive cruise control mode, the system assumes the vehicle is towing a heavier load. The gap distance between the vehicle and the vehicle in front will increase, allowing for greater stopping distance.
For vehicles equipped with a 6.7L diesel engine, the adaptive cruise control system will also use engine braking to automatically slow the vehicle speed on downward grades, to maintain a safe distance between the vehicle and the vehicle in front. If the engine brake ON or AUTO is selected, the driver will experience additional engine braking, reducing the need to apply the brakes.
When a vehicle is traveling downward on a grade, the brakes will still engage while in normal cruise control mode to slow the vehicle if it exceeds the set speed.