Fluid Pressure Sensor/Switch: Description and Operation
DESCRIPTIONThe "Transmission Gear Switches" are a set of pressure operated, normally open switches inside the automatic transaxle valve body.
OPERATION
Fluid pressure closes the appropriate switch when that gear is engaged. The PCM applies a reference voltage to each switch and then monitors the voltage in the circuit. When a switch closes, it grounds that circuit, causing a drop in the circuit voltage. Low voltage in the reference circuit to the first gear switch, for example, indicates that 1st gear is engaged.