P057B

P057B00

Diagnostic information - DME control unit

Brake light switch

DANGER
High voltage.
Death or severe injuries due to high voltage or high current.

- De-energise the vehicle in accordance with the guidelines.
- Work must not be performed on parts carrying a high voltage.

The control unit must be active in order to test internal function sequences and diagnosable inputs/outputs.
In the event of a fault, check whether the fault is permanently >present<. To perform the check, erase the fault memory, meet the diagnostic conditions and read out the fault memory again.

NOTE:
Brake pedal monitoring: since the fuel injection system operates with an electronic accelerator pedal that may develop a fault at some time, the engine speed is governed when the brake is operated. For this purpose, the signals of the brake light switch - F and brake pedal switch - F47 are evaluated in the engine control unit. If the brake is operated with depressed accelerator pedal, the engine speed is immediately governed to idle speed. Undesired governing operations may occur due to incorrect switch settings.

- The cruise control is deactivated

Diagnostic conditions
- Brake light switch, plausibility fault

Possible fault causes
- Signal implausible
- Electrical fault in circuit