Steering Wheel Switches

WARNING: This page is about a different car, the 2018 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.

The RH upper and lower steering wheel switches contain series of resistors. Each steering wheel switch function corresponds with a specific resistance value within the switch.

The SCCM sends a 5-volt reference voltage to the RH upper and lower steering wheel switches on the input circuit. When a switch is pressed, the voltage is routed through the corresponding resistor(s), through the return circuit, and then to ground through the SCCM. The SCCM monitors the resultant voltage drop to determine which switch was pressed. The voltage drop varies depending upon the resistance of the specific switch pressed.

The RH upper steering wheel switch inputs are sent as network messages from the SCCM to the IPC to control the IPC infotainment display.

The RH lower steering wheel switch inputs are sent as network messages from the SCCM to the APIM to control SYNC ® functions, or to the ACM to control audio functions.