Adaptive Speed Control

The vehicle operator controls all Adaptive Speed Control (ACC) system features through the speed control switch pod on the face of the right horizontal spoke of the steering wheel. When a push button of the switch pod is depressed, it provides a LIN switch input to the Steering Column Control Module (SCCM).

The SCCM reads the speed control switch input, then relays an electronic speed control switch status message to the Powertrain Control Module (PCM) and to the ACC module over the Controller Area Network (CAN) data bus. The PCM and ACC module continually monitor these inputs as well as electronic wheel speed message inputs from the Antilock Brake System Module (ABS), electronic gear selector message inputs from the Transmission Control Module (TCM), and numerous hard wired inputs including the brake (stop) lamp sensor, then provides the appropriate electronic message and hard wired outputs to invoke the requested electronic speed control features.

Using the MODE push button of the speed control switch pod on the face of the right horizontal spoke of the steering wheel, the vehicle operator can choose between adaptive speed control and conventional speed control modes of operation. As the name implies, when in the conventional speed control mode the speed control system is used and functions exactly like a conventional speed control system. When in the adaptive speed control mode, the vehicle operator can use the DISTANCE increase or decrease push buttons of the speed control switch pod to select from one of three distance settings for the adaptive cruise system to maintain. These settings equate to the time in seconds separating the vehicle from a preceding vehicle. The ACC module sends electronic message outputs to the ABS, the TCM and the PCM to maintain the selected separation distance. The available distance settings are:

• 1  - 1.0 second
• 2  - 1.5 seconds
• 3  - 2.0 seconds

If the PCM detects a fault on one of the following systems, it will disable the cruise control system. The PCM will store an appropriate DTC.

• Engine Speed Sensor
• Sensor or actuators of the electric throttle (only for gasoline engines)
• Accelerator Pedal Potentiometer (APP Sensor)
• Brake Pedal Position
• Clutch Switch rationality
• Engine Load sensor (only for gasoline engines)
• Ignition Coils (only for gasoline engines)
• Fuel Injectors
• Turbo sensors or actuators

The PCM and ACC module continuously monitor all of the speed control system electrical circuits to determine the system readiness and accuracy. If the PCM or ACC module detects a monitored system fault, it sets and stores a Diagnostic Trouble Code (DTC). The PCM and ACC components use On-Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the diagnostic scan tool using the CAN data bus. This method of communication is used for control of the Malfunction Indicator Lamp (MIL) (also known as the Check Engine lamp) in the Instrument Cluster (IC) and for system diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel.

The hard wired inputs and outputs for the PCM and the ACC module may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the PCM, the ACC module or the electronic controls or communication between other modules and devices that provide features of the adaptive speed control system. The most reliable, efficient, and accurate means to diagnose the PCM, the ACC module or the electronic controls and communication related to speed control system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.