Part I
Exterior Lighting
Exterior lighting
The exterior lights allows the owner to identify the vehicle and signal driving manoeuvres during both the day and night. The vehicle lights illuminate the vehicle driving area. The exterior lights thus contribute to active safety in traffic.
The exterior lights can be classified according to the following categories:
- Front
- Side
- Rear
The national-market version for European standard equipment of the exterior lights contains the following:
- Halogen headlights
- Positioning light
- Parking lamps
- Driving light
- Daytime running lights
- High-beam headlight and headlight flasher
- Automatic headlamp control
- Turn indicator
- Front
- Side
- Rear
- Tail lights
- Brake lamp
- Centre high-mount stop lamp
- Number plate light
- Reversing lights
- Rear foglamp
Xenon headlights, LED headlights, Adaptive Headlights and high-beam assistant are available as optional equipment for the exterior lighting.
The following graphic shows the control units with functionality related to the exterior lights using F13 as an example.
Brief component description
Descriptions of the following components of the exterior lighting are provided:
- Footwell module (FRM)
- Headlight
- Headlight driver module
- Rear light
- Turn signals
- Hazard warning flasher switch
- Centre high-mount stop lamp
- Side-marker light
- Number plate light
- Operating facility for light
- Turn signal/high beam switch
- Steering column switch centre (SZL)
- Rain-light-solar-condensation sensor
- Roof function centre (FZD)
- Car access system (CAS)
- Integrated chassis management (ICM)
- Crash Safety Module (ACSM)
- Electronic transmission control (EGS)
- Camera-based driver support systems (KAFAS)
- Junction Box Electronics (JBE)
- Central gateway module (ZGM)
- Controller (CON)
Footwell module (FRM)
All functions of the exterior lights are controlled by the footwell module (FRM).
The footwell module (FRM) receives many input signals that cause the headlights to be switched on.The footwell module (FRM) forms the interface to the instrument cluster (KOMBI). It enables communication between the LIN bus and the K-CAN and therefore message transmission to the respective other data bus.
Headlight
The headlights are fitted above the bumper panel.The turn indicators and side marker lights are integrated in the headlights. The following graphic shows the headlights using the F10 with bi xenon headlights as an example.
The following graphic shows the rear side of the bi-xenon headlight.
Headlight driver module
The headlight driver module is fitted as a printed circuit board in the headlight.The headlight driver module evaluates the signals sent from the footwell module (FRM) via the LIN bus. In this process, the headlight driver module assumes control of the following lighting functions of the headlight:
- Parking lamps
- Daytime running lights
- Side marker light
- Turn signals
- Positioning light
Besides the lighting functions, the headlight driver module also controls the stepper motors of the headlight beam throw adjustment and of the adaptive headlight.
Taillamp
The rear lights are split into two parts. The part with the turn indicators is fitted in the outer side wall. The part with the reversing lights and the rear fog light is fitted in the tailgate. All lighting functions in the rear lights apart from the rear fog lights and reversing lights are carried out by LEDs. The lighting functions are:
- Tail lights
- Brake lamp
- Turn signals
- Side-marker light
- Reversing lights
- Rear fog light (European market version)
- Brake Force Display (US national-market version)
The following graphic shows the distribution of the lights using the left rear light of the F13 as an example.
Turn indicator
The turn indicators are activated by the footwell module (FRM). Depending on the requirements, either all turn indicators or just the turn indicators on a single side are activated.
The footwell module (FRM) receives many input signals that cause the turn indicators to be switched on.The input signals are read directly into the footwell module (FRM) or are received via K CAN2
The front turn indicators are part of the headlights. The rear turn indicators are fitted in the outer elements of the rear lights.
The side turn indicators are fitted in the side wall on each side, shown here on the F10 (available in the exterior mirrors as an option from 07/2012).
Hazard warning switch
The hazard warning switch is fitted in the fresh air grille in the centre of the dashboard. The hazard warning switch comprises a single assembly in combination with the central locking button.
The hazard warning flashers are activated by pressing the hazard warning switch. This activates all of the turn indicators at once, while the display in the hazard warning switch flashes.
If the turn signal/high beam switch is pressed in the direction for left or right turns while the hazard warning flashers are operating, the turn indicator light assumes priority. The hazard warning flashers are reactivated after "Terminal 15 off" or when the turn indicator has stopped.If the hazard warning switch is depressed while the turn indicator lights are operating, then the hazard warning flashers assume priority.
With "Terminal 30 on" the hazard warning flashers are implemented in their energy-saving mode. In this mode, the hazard warning flashers light up for a shorter period and remain off for a longer period than usual.
When the anti-theft alarm system is signalling an active alarm the hazard warning switch is suppressed and does not flash with the alarm system.
The hazard warning flashers are switched on automatically during an emergency braking situation.
Additional brake light
The additional brake lights are LEDs.
The footwell module (FRM) activates the additional brake light together with the Brake lights in the rear lights.
An interference suppression filter is integrated in the circuit upstream from the additional brake light. The interference suppression filter enhances electromagnetic compatibility and prevents interference from affecting other components, such as the rear window aerial.
Side-marker light
The side marker lights are installed in each headlight above the turn indicator. The rear side marker lights are fitted in the upper part of the rear lights.
Number plate light
The number plate lights are LEDs. These light-emitting diodes are integrated within the handle strip of the tailgate. Each number plate light contains 2 LEDs.
Operating facility for light
The exterior lights can be switched on and off at the operating facility for lights.
The operating facility for lights includes both the light switch and other components.
The following table shows which terminals must be active before the exterior lights can be switched on.
Turn signal/high beam switch
The turn indicators and the high-beam headlight are controlled by turn signal/high beam switch on the steering column switch cluster (SZL). The signal from the turn signal/high beam switch is transmitted both via FlexRay protocol and through a separate line to ensure functional redundancy. This increases system availability in the event of a fault. The turn indicator lights continue to operate, even if the information fails to reach the footwell module (FRM) through the bus system. This redundant data-transmission is also employed for one-touch flashing function and for the headlight flasher.
The steering column switch cluster (SZL) transmits the signal from the turn signal/high beam switch via FlexRay. The central gateway module (ZGM) transmits the signal to K CAN2. This is how the footwell module (FRM) receives the signals from the turn signal/high beam switch.
Steering column switch centre (SZL)
The steering column switch cluster (SZL) features one steering column switch each on the left and right sides. The right-hand steering column switch controls the functions of the wash/wipe system. The steering column switch on the left side of the steering column controls the high-beam headlight and turn indicators as well as operation of the on-board computer.
The signals are made available by the steering column switch cluster (SZL) via the FlexRay. The signals of the integrated steering angle sensor are also transmitted to the Integrated Chassis Management (ICM) via the FlexRay.
For the exterior lights the footwell module (FRM) receives the following commands from the steering column switch cluster (SZL):
- Turn indicator light
- Parking lamps
- High-beam headlamps
- Headlamp flasher
- High-beam assistant
- "Follow-me-home" lighting
