Accelerator Pedal Position Sensor

Courtesy of VOLVO CARS CORPORATION

The function of the accelerator pedal position sensor is to provide the Engine Control Module (ECM) with information about the position of the accelerator pedal.

The sensor consists of a plastic housing with two contactless inductive type sensors, each with a driving circuit for generating signals. The sensors' moving parts are connected to a shaft which is influenced by the accelerator pedal position. The output signal from the sensors changes with the accelerator position.

The Engine Control Module (ECM) checks the PWM signal and the analogue signal from the accelerator pedal position sensor. The analogue signal is directly connected to the Central Electronic Module (CEM) and the signal is sent via CAN communication to the Engine Control Module (ECM). The PWM signal is directly connected to the Engine Control Module (ECM).

In a fault-free system, the PWM signal is used to determine the current accelerator pedal position.

The sensor for the PWM signal is supplied with 12 V by the system relay via a fuse and is grounded to the body frame. The sensor's analogue section is supplied with 5 V from the Central Electronic Module (CEM) where grounding also occurs.

The digital signal is used together with the analogue signal to diagnose the accelerator pedal sensor. The accelerator pedal position sensor's signals can be read out using the diagnostic tool. If the Engine Control Module (ECM) detects a difference between the analogue and digital signal, a DTC is set and the Engine Control Module (ECM) then uses a minimum value to ensure function (limp-home). If a fault occurs in any of the sensors, the throttle response is slower. If the Engine Control Module (ECM) cannot detect which of the sensors is faulty, the signal with the lowest value is always used.

The accelerator pedal position sensor is located on the accelerator pedal bracket.