Circuit Description

The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits:

• A 5-volt reference circuit
• A low reference circuit
• A signal circuit

The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is also low at rest and increases as the pedal is depressed.

This DTC incorporates the following diagnostic tests:

• The APP sensor 1 to APP sensor 2 correlation
• The accelerator pedal minimum position correlation between the APP sensor 1 and APP sensor 2
• The APP sensor 1 signal shorted to a 5-volt reference, ground, or the APP sensor 2 signal

If the PCM detects one or more of the APP sensor 1 tests are out of range, DTC P2121 sets.