Switch, Speed Control: Operation

WARNING: This page is about a different car, the 2020 Chrysler 300 and 2019 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

The speed control switch pod is a Local Interface Network (LIN) slave unit that provides LIN bussed inputs to the Steering Column Control Module (SCCM) microcontroller.
The driver acts on the speed control switch assembly installed into the steering column.
The SCCM acquires LIN inputs from the speed control push button assembly and then transmits the status via the Controller Area Network-Chassis (CAN-C) network to the Powertrain Control Module (PCM).
The PCM manages the cruise control algorithm to maintain vehicle speed established by the driver. It is also the responsibility of the PCM to send out cruise control override information and perform stuck button diagnostics.
The radio switch resistive ladder inputs are read by the steering wheel switch bank and broadcasts the signals on the LIN bus.

The speed control switch pod for vehicles equipped with a conventional electronic speed control system and not equipped with the optional Adaptive Cruise Control (ACC) system contains five switch push buttons whose functions are:

On/Off - This switch button enables or disables the speed control system and clears any previous speed control set speed from system memory.
Set (+) - This switch button sets the current vehicle speed as the stored set speed or accelerates the vehicle to a speed that is faster than the already attained set speed.
Set / (-) - This switch button sets the current vehicle speed as the stored set speed or decelerates (coasts) the vehicle to a speed that is slower than the already attained set speed.
Resume / (+) - Resume is a momentary switch that allows the driver to re-engage Cruise Control to the last stored vehicle speed, provided that the cruise control system is still enabled and current vehicle speed is greater than the calibrated minimum resume speed.
Cancel - This switch button cancels the current speed control event, but does not turn the system OFF or clear the currently stored set speed.

The optional adaptive speed control switch pod for vehicles equipped with the ACC system option contains the same five switch push buttons as the conventional speed control switch pod, then adds three buttons whose functions are:

Mode - This switch button toggles the speed control system between ACC or conventional (non-ACC) modes of operation.
Distance Buttons - These switch buttons select the separation or following distance (in seconds) that the ACC system maintains between this vehicle and any preceding vehicle.

The SCCM LIN master node provides a clean ground and fused B(+) current for all of the switches and sensors on the rotating steering wheel through the LIN slave node circuitry of the speed control switch pod as well as for the Light Emitting Diode (LED) backlighting of both the speed control and the EVIC switch pods. The SCCM continually monitors all of the hardwired speed control switch circuits as well as the LIN bus data. The SCCM will set a Diagnostic Trouble Code (DTC) for any problem it detects in the speed control switch circuits, and will store a Signal Not Available (SNA) code for any LIN bus input errors. The SCCM also communicates with other Electronic Control Units (ECUs) over the CAN data bus. Therefore, any SCCM DTC information can be retrieved using a diagnostic scan tool connected to the Data Link Connector (DLC).