427 Accelerator Pedal Potentiometer 1 - Above Limit

P1577

427 Accelerator Pedal Potentiometer 1 - Above Limit

Function
The angle (position) of the accelerator pedal is calculated from the potentiometer voltage of the pedal sensor. The pedal sensor features two potentiometers which each have an independent 5-volt supply from the DME control module.

The second potentiometer is equipped with a series resistor the size of the bulk resistance, so that its characteristic only has half the inclination of potentiometer 1. Various plausibility tests (voltage range, constant velocity, etc.) ensure that a single error cannot cause the angle of the accelerator pedal to take on a higher value than the actual pedal position.

Diagnosis conditions
- Ignition on (approx. 30 sec.)
- Battery voltage > 7 V

P1577:

NOTE:
- The system operates in pedal sensor standby mode, i.e. the angle of the accelerator pedal is calculated from the residual potentiometer signal.
- The maximum pedal value is limited to 40 % and the increase in the pedal value equals 10 % per sec. maximum.

Wiring Diagram







Diagnosis Procedure










1 Check wiring from DME control module, pin IV/8, to pedal sensor, pin 2, for short circuit to ground.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Connect ohmmeter to special tool, pin IV/8, and ground.

Display: infinity ohms

If 0 - 5 ohms is displayed, check wiring for chafing and pinching damage.

2 Check wiring from DME control module, pin IV/8, to pedal sensor, pin 2, for short circuit to B+.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Connect voltmeter to special tool, pin IV/8, and ground.
3. Switch on the ignition.

Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.