Circuit Description

The DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation diagnostic monitors the APP sensor 1 signal circuit. The accelerator pedal assembly contains 2 APP sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The powertrain control module (PCM) supplies a separate 5-volt reference and low reference circuit for each of the APP sensors.

The APP sensor 1 signal voltage increases as the pedal is depressed, from approximately 0.75 volt at rest to about 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 1.6 volts at rest to more than 4.8 volts with the accelerator pedal fully depressed.