Accelerator Pedal Position Sensor: Description and Operation

ACCELERATOR PEDAL POSITION (APP) SENSOR




The accelerator pedal position (APP) sensor (1) is fastened to the accelerator pedal assembly (2). The APP sensor assembly contains two APP sensors that are operated by accelerator pedal (3) movement. The APP sensors 1 and 2 are potentiometer type sensors each with 3 circuits:
- A 5-volt reference circuit
- A low reference circuit
- A signal circuit

The APP sensors are used to determine the pedal angle. The powertrain control module (PCM) provides each APP sensor with a 5-volt reference circuit and a low reference circuit. The APP sensors provide the PCM with signal voltage proportional to the pedal movement. APP sensor 1 signal voltage is low at the rest position and increases to near the 5-volt reference as the pedal is applied. APP sensor 2 signal is about twice the voltage of APP sensor 1 at rest, and also increases as the accelerator pedal is applied. APP sensor 2 increases at a different rate than APP sensor 1. The APP sensor 1 is responsible for providing the actual pedal position to the PCM. The PCM then sends a throttle position target value to the TAC control module. APP sensor 2 provides an accuracy check and if necessary, a backup value to the APP sensor 1. The APP sensors are not serviced separately and must be replaced with the accelerator pedal assembly.