Overview
This document contains the following information:
General
Overview of light functions
General
The exterior lights control all the safety and comfort-relevant functions of the front, side and rear lamps on the vehicle.
A differentiation is made between the following headlamp versions depending on the vehicle equipment involved:
Halogen headlamps
Static LED headlamp
Dynamic LED headlamp
For the following special vehicle conditions, the exterior lighting functions are only partly available:
Transport mode
Production mode
Roller mode
Check function for technical tests
To reduce the load on the on-board electrical system, the energy management requests that the exterior lighting be switched off in certain situations. This helps to avoid the on-board electrical system battery from being discharged.
Substitute light control
The function of the vehicle's rear lighting is continuously monitored. If the rear turn signal light fails, the corresponding brake light is actuated at flasher frequency as a replacement.
Emergency light system
A software emergency light function is activated if a data transfer fault occurs. The following light functions are then activated:
Taillamp
Low beam
Brake light (depending on status of circuit 54)
If the rain and light sensor fails or if communication with the rain and light sensor fails, the automatic driving lights are activated.
If, on vehicles equipped with LED headlamps, the exterior lighting control unit malfunctions, the headlamp control units activate the low beams (emergency light function). On vehicles equipped with halogen headlamps, the vehicle in this case can no longer be driven. The exterior lighting control unit is, depending on the vehicle, the central signal acquisition and actuation module or the front signal acquisition and actuation module.
On model 118, 177, 247, the brake light is actuated permanently if the Electronic Stability Program (ESP®) malfunctions.
Overview of light functions
The exterior lighting includes the following light functions:
Standing and parking lights
Driving lights
Rear fog lamp
Turn signal lamp
Brake light
Backup lamp
Comfort illumination (surround lighting, locator lighting)
Various control messages are used to inform the driver about the current operating status of the exterior lighting. In certain situations the driver is also notified acoustically about active functions (e.g. turn signal light).
Subsystems | |||
Actuate standing lights and parking lights, basic function | |||
Actuate driving lights, basic function | |||
Actuate rear fog light, basic function | |||
Actuate brake lights, basic function | |||
Actuate turn signal light, basic function | |||
Actuate reversing light, basic function | |||
Comfort illumination, basic function |