Cruise Control Indicator
The ACC indicator located in the IPC illuminates in gray and the previous gap setting and SET graphic is displayed indicating the system is in standby mode. This notifies the driver the system is ready and the vehicle can be accelerated to the desired speed. When the vehicle reaches the desired speed and the SET+ is pressed, the ACC indicator illuminates in green.
The CCM is on a dedicated CAN with the IPMA. The IPMA acts as a gateway module and relays network messages and DTC information from the CCM to other modules that utilize the ACC 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 ACC. 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 ACC. ACC resumes 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 ACC may function erratically. The ACC needs to be disengaged using the menu option and the operator only haves non-adaptive cruise control functionality.
The ACC system does not engage properly if the front radar sensor is not aligned correctly and the message center displays FRONT SENSOR NOT ALIGNED. The ACC resumes once the radar is aligned and is able to properly detect targets.
The CCM radar vertical and horizontal alignment procedure is located in General Procedures. The horizontal alignment for the CCM is a calibration check performed by the scan tool to insure the CCM is pointed straight. The scan tool identifies this as, Alignment Offset with a horizontal specification of +/- 3.0 degrees offset. For additional information, Refer to: Cruise Control Radar Alignment .
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 ACC 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 disables the system.
When tow/haul mode is selected while the vehicle is operating in ACC 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.
Vehicles equipped with the diesel engine, the ACC system uses engine braking to slow the vehicle speed on downward grades or to maintain a safe distance between the vehicle and the vehicle in front. If the engine brake ON or AUTO is selected, the driver experiences additional engine braking, reducing the need to apply the brakes.
When a vehicle is traveling downward on a grade, the brakes will engage while in normal cruise control mode to slow the vehicle if it exceeds the set speed.