194001325 - E2021 BRAKE LIGHTS - DESCRIPTION

The vehicle brake lights are located at the rear in the tail-lights and in the central third brake light, consisting of 10 separate bulbs.They are operated whenever the brake pedal is pressed by means of a switch on the pedal.

the switch on the pedal consists of two contacts that supply two signals: the first NO contact detects brake pedal positions other than the rest position; the second NC contact detects the brake pedal position at rest.

The lights are turned on by the N.O. contact (pedal pressed). Information from the N.O. switch is sent in particular to the engine control unit and the ABS/ESP control unit.     See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT     See E7020 ABS     See E7023 ESPThe function is active under the following conditions:- enablement signal when key inserted and turned ON in the ignition (INT);- command signal from the above switch.The brake light check function monitors that the lights are operating correctly: the following are checked for each of the two circuits:- open circuit (bulb missing or wiring interrupted)- closed circuit to earth (bulb s.c. or wiring s.c. to earth);- short circuit to Vbatt (wiring s.c. to Vbatt).The continuity of the fuse protecting the switch on the brake pedal is also checked.When one of the above situations occurs, the Body Computer makes the fault status available via the CAN network: the "exterior lighting fault" warning light lights up on the instrument panel and the information is simultaneously shown on the display.

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

For driving safety, if one of the rear side lights is faulty, the brake light bulb on the corresponding side lights up with a dim light (5W) to simluate the brightness of the side light.