Accelerator Pedal Position Sensor: Description and Operation

Accelerator Pedal (AP) Position Sensor







The function of the accelerator pedal (AP) position sensor is to provide the engine control module (ECM) and central electronic module (CEM) with information about the position of the accelerator pedal. This data is used by the engine control module (ECM) to deploy the shutter in the throttle unit to the correct angle.

The sensor consists of a plastic housing with circuits. The output signals are a pulse width modulated (PWM) signal and an analog signal related to the accelerator pedal (AP) position. These signals indicate the position of the accelerator pedal (AP). The pulse width modulation (PWM) signal is transmitted to the engine control module (ECM). The analog signal is transmitted to the central electronic module (CEM) and on to the engine control module (ECM) via the controller area network (CAN).

Normally the pulse width modulation (PWM) signal is used to regulate the throttle angle. In the event of a fault in the pulse width modulation (PWM) signal the analog signal is used as a replacement, unless this is also diagnosed as faulty.

The sensor is supplied with 12 V by the system relay via a fuse and is grounded in the car body. The pulse width modulation (PWM) signal is also used in conjunction with the analog signal for accelerator pedal (AP) position sensor diagnostics. The accelerator pedal (AP) position sensor signals can be read using Vehicle Information and Diagnostics Application (VIDA). A diagnostic trouble code (DTC) is stored if the engine control module (ECM) detects a difference between the analog and pulse width modulation (PWM) signals. The engine control module (ECM) then uses the signal with the lowest value for regulation.

The accelerator pedal (AP) position sensor is located on the accelerator pedal bracket.