Throttle Position Sensor

Throttle-Valve Potentiometer

The throttle-valve potentiometers represent an integral part of the electric throttle valve actuator EDK. They determine the current position of the throttle valve and transfer the signals in the form of a voltage signal to the DME control module.

Two separate throttle-valve potentiometers are used for the S54 engine. One potentiometer is located on the throttle shaft and the other potentiometer is fitted on the actuator. The voltage signals vary dependent on the position of the throttle valve, i.e. for potentiometer on the throttle shaft between 0.5 V and 4.5 V and in the opposite direction for potentiometer on the actuator between 4.5 V and 0.5 V.

When the accelerator pedal is pressed from idle to full load the voltage signal must increase constantly for the one potentiometer and decrease continuously for the other potentiometer. The "idle" status must be indicated when the accelerator pedal is not operated.

Throttle-valve potentiometer adaptation must be deleted after replacing or repairing the potentiometer.

If a fault occurs during operation a corresponding fault code will be stored in the fault memory of the DME control module.

A special system test can be initiated in the diagnosis program via the DIS tester/MoDiC. This throttle test procedure is used to test the function of the throttle valve and of the potentiometers.

Monitoring functions
The following monitoring functions are realized in the DME control module for the throttle-valve potentiometers:
- Monitoring of both potentiometers for electrical faults
- The potentiometer on the throttle shaft is the control potentiometer
- The potentiometer on the actuator is the reference for the potentiometer on the throttle shaft
- Plausibility monitoring of both potentiometer signals with respect to each other