S126 Drive Mode Select Switch

The S126 Drive Mode Select Switch is a momentary button with one switches. At rest, the S126 Drive Mode Select Switch remains in a neutral position with the switche open. When the AWD button is pressed, the switch is closed. When released, the switch returns to the neutral position and the switch will again be open. The switch is situated within a resistor ladder. The K20 Engine Control Module applies 5 volts to the resistor ladder, which also receives a constant ground. The K20 Engine Control Module monitors the signal voltage. The signal voltage is measured within the resistor ladder. When the switch is closed, current flows through a different number of resistors, changing the voltage drop across the resistors and changing the voltage monitored by the K20 Engine Control Module.