Steering Wheel Switch - Message Center
WARNING: This page is about a different car, the 2013 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The message center switch portion of the LH steering wheel switch is comprised of 5 buttons. Each button operates a unique switch within the message center switch portion of the LH steering wheel switch assembly. Each button uses a different resistance value. The SCCM sends out a reference voltage to the LH steering wheel switch on the input circuit and monitors the voltage drop when a message center switch button is pressed. The voltage drop varies depending upon the resistance of the specific button pressed, indicating to the SCCM which switch is pressed.