Two switches are fitted on the brake pedal which supply the following signals:
The DDE control unit evaluates the signals for the purpose of registering brake operation.
The brake light switch switches to ground, the brake light test switch to B+. The plausibility of both signals is checked.
The following table shows how the signals behave:
|
Brake light switch is |
Brake light test switch is |
Brake pedal operated |
open |
closed |
Brake pedal not operated |
closed |
open |
Fault code 1A "brake light/brake test switch" is stored if the signals are not plausible. Cruise control is deactivated as a result.