Pedals position- sensors engine operation-9-




The APP sensor identifies the current position of the accelerator and sends this to the PCM and the GEM.
The APPsensor is a double contactless inductive sensor. The APP sensor is integrated with the accelerator pedal in the accelerator pedal module.
The inductive sensor essentially works in a similar way to a transformer. The incoming DC voltage first has to be converted into AC voltage. Depressing the accelerator pedal moves a rotor. This rotor induces the AC voltage between the primary coil and the secondary coil.
In the APP sensor the signals are split as follows:
  • APP 1 = PWM signal to the GEM and from there via the CAN data bus to the PCM.
  • APP 2 = the analogue DC (direct current) signal is sent directly to the PCM.
Both signals are monitored by the PCM for plausibility.
If one of the two APP sensors fails then the vehicle drives with reduced acceleration. Top speed can nevertheless be achieved.
If both of the APP sensors fail, the engine is regulated to a defined speed following a plausibility check after the BPP switch and brake light switch have been actuated once. The vehicle can then only be accelerated to a defined speed.
In either case, a fault is saved in the error memory of the PCM.

Clutch pedal position (CPP) switch

The CPP switch sends an earth signal to the GEM as soon as the clutch is depressed. This signal is passed on by the GEM via the CAN databus to the PCM. The PCM needs this signal to improve engine running performance during switching processes.
Failure of the CPP switch can cause the engine to judder during the switching process.


Brake pedal position (BPP) switch


The BPP switch tells the PCM whether the vehicle is being braked. In its rest state the switch is closed and sends an earth signal to the GEM. This signal is sent to the CAN via the PCM databus.
The brake light switch is likewise connected to the GEM and is opened in the rest state. When the vehicle is braked, the brake light switch sends a signal to the GEM. This compares the signals from the BPP switch and the brake light switch. If a discrepancy occurs, a fault is stored in the error memory of the GEM.
Information from both switches is needed for emergency operation if the APP sensor fails.
If the APP sensor fails and the BPP switch is actuated, the engine is set to idle speed via the

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