Steering Wheel Switches - Vehicles Built On Or After July 8, 2013
WARNING: This page is about a different car, the 2014 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.
The RH upper steering wheel switch contains a series of resistors. Each steering wheel switch function corresponds with a specific resistance value within the switch.
The APIM sends a 5-volt reference voltage to the RH upper steering wheel switch on the input circuits. When a switch is pressed, the voltage is routed through the corresponding resistor(s), and is then routed to ground through the APIM . The APIM monitors the resultant voltage drop to determine which switch was pressed. The voltage drop varies depending upon the resistance of the specific switch pressed.