Accelerator Pedal Position Sensor: Description and Operation

The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually three individual Accelerator Pedal Position sensors within one housing. Three separate signal, ground and 5.0 volt reference circuits are used to connect the Accelerator Pedal Position Sensor assembly and the Throttle Actuator Control (TAC) Module. Each sensor has a unique functionality. The APP sensor 1 signal increases as the accelerator pedal is depressed, from below 1 volt at 0% pedal travel (pedal at rest) to above 2.0 volts at 100% pedal travel (pedal fully depressed). The APP sensor 2 signal decreases from above 4.0 volts at 0% pedal travel to below 2.9 volts at 100% pedal travel. The APP sensor 3 signal also decreases from above 3.8 volts at 0% pedal travel to below 3.1 volts at 100% pedal travel. Observe that the signal circuits for APP Sensor 2 and APP Sensor 3 are pulled up to 5.0 volts and the APP Sensor 1 signal circuit is referenced to ground within the TAC Module.

When the PCM detects a malfunction with the APP sensor circuits, the following DTCs will set:
^ DTC P1125 APP System.
^ DTC P1275 APP Sensor 1 Circuit.
^ DTC P1276 APP Sensor 1 Circuit Performance.
^ DTC P1280 APP Sensor 2 Circuit.
^ DTC P1281 APP Sensor 2 Circuit Performance.
^ DTC P1285 APP Sensor 3 Circuit.
^ DTC P1286 APP Sensor 3 Circuit Performance.