2427916 - E2021 BRAKE LIGHTS - Description

Description

The brake lights are located at the rear in the side lights and in the central third brake light and consist of 10 separate bulbs. These are operated whenever the brake pedal is pressed, by means of a switch on the pedal itself.
the switch fitted on the pedal assembly consists of two contacts which supply two signals: the first which is the 'N.A.' type recognizes the position of the brake pedal when it differs from the rest position, i.e. pedal pressed; the second, which is the 'N.C.' type, recognizes the brake pedal in the rest position. The lights are turned on by the 'N.A.' contact (pedal pressed). The 'N.A.' switch information is sent via the CAN, in particular to the engine management control unit and the ABS control unit.  See E5030  PETROL ENGINE ELECTRONIC MANAGEMENT ,  See E5050  DIESEL ENGINES ELECTRONIC MANAGEMENT ,  See E7020  ABS ,  See E7023  ESP .
The control function is activated by the go ahead signals from the key in the ON position (INT) and the contact for the above mentioned switch.

The correct operation of the side lights is controlled by the brake lights 'check' function: the following are checked:

  • open circuit (bulb missing or wiring broken) which can be diagnosed without a command
  • short circuit to earth (bulb short circuit or wiring short circuit to earth)
  • short circuit to Vbatt (wiring short circuit to Vbatt)
The continuity of the fuse protecting the switch on the brake pedal is also checked.If one of the situations described above is detected, the Body Computer notifies the CAN of the failure state: a special 'failure' warning light comes on in the instrument panel and, at the same time, the information is shown on the display.
The switching on of the side brake lights is managed by the Body Computer and that of the third brake light is managed directly by the switch on the pedal.