939011504 - E2021 BRAKE LIGHTS - DESCRIPTION

DESCRIPTION

The vehicle brake lights are located at the rear in the side lights (by means of a red double filament bulb together with the side light) and in the special centre third brake light mad up of 10 all glass type bulbs.They are operated each time the brake pedal is pressed via the special switch on the actual pedal.

the switch fitted on the pedals consists of two contacts which supply two signals: the first is the N.A. type and recognizes the position of the brake pedal if it is not in the rest postion, i.e. the pedal is pressed; the second is the N.C. type and recognizes the position of the brake pedal in the rest position.The lights are turned on by the N.A. contact (pedal pressed). Information from the N.A. switch is sent in particular to the engine management control unit and the ABS control unit, VDC function.    See E7022 VDC

The control function is activated by the TEG inserted enablement signals (INT) and the command from the switch contact.The brake light check function monitors that the side lights are operating correctly: the following are checked:- open circuit (bulb missing or wiring interrupted)- short-circuit to earth (bulb s.c. or wiring s.c. to earth)- short circuit to battery voltage (wiring short circuited to Vbatt)The continuity of the fuse protecting the switch on the brake pedal is also checked.When one of the situations described above is ascertained, the Body Computer makes the failure status available to the CAN: a special "lights failure" warning light comes on in the instrument panel and, at the same time, the information is shown in the display by means of the specific symbol.

the central brake light is controlled directly by the switch on the pedal and is not subject to checking.