Conventional Speed Control

The vehicle operator controls all conventional speed control 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 hardwired resistor multiplexed analog input to the Steering Column Control Module (SCCM) microcontroller.

The SCCM microcontroller reads the speed control switch input via LIN, then relays an electronic speed control switch  status message to the Powertrain Control Module (PCM) over the Controller Area Network (CAN) C data bus. The PCM software continually monitors these inputs as well as electronic vehicle distance  message inputs from the Antilock Brake Module (ABM) (also known as the Controller Antilock Brake/CAB, the Electronic Stability Control/ESC module or the Antilock Brake System/ABS module) and numerous hardwired inputs including the brake (or stop) lamp switch, then provides the appropriate electronic message and hardwired outputs to invoke the requested electronic speed control features.

The PCM microcontroller continuously monitors all of the speed control system electrical circuits to determine the system readiness. If the PCM detects a monitored system fault, it sets and stores a Diagnostic Trouble Code (DTC). The PCM uses 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 ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) and for system diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel.

If the ECM/PCM detects a fault on one of the following systems, it will disable the cruise control system. The ECM/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
• High pressure system components (only for GDI and Diesel engines)
• Turbo sensors or actuators.

The hardwired inputs and outputs for the PCM 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 or the electronic controls or communication between other modules and devices that provide features of the conventional speed control system. The most reliable, efficient, and accurate means to diagnose the PCM 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.