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Accelerator pedal position sensor

Accelerator pedal position sensor



The task of the position sensor is to convert the request from the driver from a pedal position to an instruction that the engine control module can understand and process. It is controlled by the accelerator pedal via a cable that turns the shaft in the position sensor.

There are two potentiometers inside the position sensor. They vary the voltage to the sensor inputs of the control module depending on the angle of the position sensor shaft. The position sensor consists of resistance tracks with collector shoes. The collector shoes are mounted on the shaft of the position sensor and move over the resistance tracks in relationship to the movements of the shaft.

Power is supplied to the potentiometers with 5 V from pins 31 and 7 on the control module to pins 5 and 2 on the sensor. The sensor is grounded through pins 6 and 4 on the sensor to pins 21 and 9 on the control module.

The sensor inputs of the control module, pins 45 and 33, are connected to pins 1 and 4 on the position sensor, where voltage varies in relationship to the angle of the sensor shaft.

So that correct information is obtained from the position sensor, it is divided into two different potentiometers. Both are supplied with 5 V, but the signal to the control module is always twice as much on P1as on P2, 0-5 V on the one and 0-2.5 V on the other. This is to ensure both the function and diagnosis of the position sensor. See the illustration of the sensor's inner coupling.

When the position sensor angle is less than approx. 9°, the potentiometers are idling and voltage to the control module input terminals is less than 1.1 V and 0.55 V respectively.

Diagnosis


• If pedal position sensor 1 is short-circuited to B+, DTC P0123 will be generated.

• If pedal position sensor 2 is short-circuited to B+, DTC P0223 will be generated.

• If the connector is not connected, DTC P1122 will be generated.

• If there is a plausibility fault between circuits 1 and 2, DTC P1271 will be generated.


Regardless of which potentiometer has the fault, the DTCs will be set. All pedal position faults set an idle speed of approx. 1400 rpm.

The pedal position sensor is replaced as a complete unit.