Switch, Speed Control: Operation
The speed control switch pod is a resistor multiplexed unit that provides hard-wired inputs to the Body Control Module (BCM). The BCM relays the speed control switch inputs to the Powertrain Control Module (PCM) over the Controller Area Network (CAN) bus.
The speed control switch contains four control functions, which are:
- On/Off - Enables or disables the speed control system and clears any previous speed control set speed stored within the system memory.
- Resume / + - Restores the vehicle speed to the previously stored set speed or accelerates the vehicle from the set speed.
- Cancel - Cancels the current set speed control event, but does not turn the system OFF or clear the currently stored set speed.
- Set / - - Sets and stores the current vehicle speed or decelerates the vehicle to a speed that is slower than the set speed.
The BCM continually monitors all of the hard-wired speed control switch circuits and will set a Diagnostic Trouble Code (DTC) for any problem it detects in the speed control switch circuits.
The analog resistor multiplexed circuits of the speed control switch stalk, as well as the hard-wired circuits between the switch stalk and the BCM, 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 BCM, the PCM or the electronic controls and communication between modules and other devices that provide some features of the speed control system. The most reliable, efficient, and accurate means to diagnose the speed control switch pod, the BCM, 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.