Part II

Exterior Lighting

Rain-light-solar-condensation sensor
The rain-light-solar-condensation sensor receives its voltage supply from the roof function centre (FZD) and consists of the following sensors:
1. Rain sensor
2. Photosensor
3. Solar sensor
4. Condensation sensor

The 2 photosensors measure the surrounding area brightness and the near field to the vehicle. The photosensors supply the signal for switching the automatic driving lights control on or off.







Roof function centre (FZD)
The roof function centre (FZD) with its integrated ultrasonic interior movement detector provides the signal for the optical alarm via K CAN2. The footwell module (FRM) can then allow the anti-theft alarm system to provide a optical alarm using the turn indicators.
The roof function centre (FZD) supplies the rain-light-solar-condensation sensor with voltage.
The following graphic shows the high version using the F13 as an example.







Car access system (CAS)
The Car Access System (CAS) is the control unit that regulates access to the vehicle (key identification). It checks the prerequisites for release before the junction box electronics (JBE) and the footwell module (FRM) are activated.The Car Access System (CAS) is directly connected to the K-CAN2.The Car Access System (CAS) prepares signals and makes these available to other bus users in the vehicle electrical system.
The Car Access System (CAS) furnishes the brake-light switch with a 5-volt voltage supply. The Car Access System (CAS) processes the status of the brake-light switch and transmits it through K CAN2. The footwell module (FRM) receives the status of the brake-light switch and uses it in controlling activation of the brake light.







Integrated chassis management (ICM)
Data from ride height sensors at the front and rear axle is evaluated by the Integrated Chassis Management (ICM).The automatic headlight beam throw adjustment thus ensures that oncoming traffic is not dazzled. In addition to the sensors for driving dynamics control, the Integrated Chassis Management (ICM) includes a longitudinal and a lateral acceleration sensor for impact detection.Two wires provide a direct connection between the Integrated Chassis Management (ICM) and the Crash Safety Module (ACSM) for transmission of the sensor signals.The footwell module (FRM) receives signals from the Integrated Chassis Management (ICM) through the K-CAN2. Within the central gateway module (ZGM) the FlexRay transfers the signal to K CAN2.







Crash Safety Module (ACSM)
The Crash Safety Module (ACSM) is the control unit for the passive safety system. The Crash Safety Module (ACSM) evaluates the longitudinal acceleration and lateral acceleration sensor signals. The direction and accident severity are determined based on the acceleration data. Comprehensive tests are used to define triggering thresholds for all possible types of accident. This leads to different triggering thresholds for activation of the various restraint systems. In the event of an impact, the Crash Safety Module (ACSM) determines whether deployment is required and which gas generators should be ignited. The Crash Safety Module (ACSM) transmits a message to other bus users when the restraint systems are triggered. Depending on accident severity, each of the control units performs certain functions, as exemplified by the footwell module (FRM), which responds by switching on the hazard warning flashers.







Electronic transmission control (EGS)
The electronic transmission control (EGS) transmits information on the engagement status of reverse gear. This information is processed in the footwell module (FRM). The reversing lights are activated based on the received information.
On vehicles with manual gearboxes, the signal is supplied by the reversing light switch.
The automatic transmission is controlled by the mechatronics module. The mechatronics module is a combination hydraulic unit and electronics module. The hydraulic unit engages the gearbox.
The electronics module contains the electronic transmission control (EGS), the sensors and the electrical connections to the inside of the gearbox.







Camera-based driver support systems (KAFAS)
Depending on the options fitted, various camera-based systems are available. The light points, light colours and light intensities picked up by the video camera are evaluated by the KAFAS control unit. The evaluation by the KAFAS control unit results in a recommendation to switch on or off the high-beam assistant.Technically, the system is implemented with a joint camera and a joint control unit, the KAFAS control unit.







Junction Box Electronics (JBE)
The Junction Box Electronics (JBE) requests information on ambient brightness from the rain-light-solar-condensation sensor through the LIN bus. The Junction Box Electronics (JBE) module transmits the status via K CAN2. The footwell module (FRM) assesses the status of the ambient brightness.







Central gateway module (ZGM)
The central gateway module (ZGM) links all of the data buses. The central gateway module's (ZGM) gateway function thus supports data exchanges amongst the various bus systems.Stored system functions can be called up using appropriate commands.







Controller (CON)
The controller (CON) is connected to the central information display (CID) via the body CAN. The controller (CON) is the central operating element for all vehicle functions that can be selected and configured on the central information display (CID). The control panel and control unit of the controller (CON) have been combined in one single component.
There are 7 fixed selector keys arranged around the controller. These selector keys now enable selection of half of all the submenus.
Specific vehicle functions can be selected and adjusted at the Central Information Display (CID). All of the functions in the exterior lights system can be selected and adjusted using the controller (CON) in the Central Information Display (CID):
- Daytime running lights
- Duration of headlight courtesy delay feature
- Optional central locking system feedback signal
- Welcome lamps
- Brief turn signal activation







System overview

Front exterior lights with automatic headlight beam throw adjustment







Exterior lights, rear







System functions
The functions of the exterior lights are integrated within the footwell module (FRM).
These lighting function are:
- Parking lamps
- Driving light
- High-beam headlight
- Headlamp flasher
- Turn indicator
- Hazard-warning flashers
- Tail lights
- Licence plate lamps
- Dynamic brake light, brake light
- Reversing lamps
- Rear fog light (European market version)
- Parking lamps
- Welcome lamps
- "Follow-me-home" lighting
- Daytime running lights

The headlight lighting functions are controlled by a headlight driver module on each side are supplied with voltage by the footwell module (FRM). The headlight driver module receives the information used to control the voltage supply to the light source from the footwell module (FRM) through the LIN bus. The LEDs, for example in the additional brake light or tail light, are 100% pulse width-activated. On vehicles with xenon headlights or LED headlights, a power distribution box is responsible for the dimming.
In addition to these lighting functions, other exterior lights functions are also integrated in the footwell module (FRM):
- Automatic headlamp control
- Dynamic headlight beam throw adjustment
- Light monitoring
- Cold monitoring at "lights off"
- Hot monitoring at "lights on"
- Optical alarm and optical feedback signal
- Central locking system
- Anti-theft alarm system
- Crash signal present
- Emergency lighting with "Terminal 15 off"
- Emergency operation
- Adaptive Headlights
- Variable light distribution

The following system functions are described:
- Side lights, low and high-beam headlight
- Bi-xenon headlights
- Welcome lamps
- "Follow-me-home" lighting
- Automatic headlamp control
- Adaptive Headlights
- Variable light distribution
- Automatic headlight beam throw adjustment
- High-beam assistant
- Turn signals
- Hazard-warning flashers
- Brake lamp
- Reversing lamps
- Rear foglamp
- Parking lamps
- Visual feedback signal from central locking system
- Emergency lighting with "Terminal 15 off"

Side lights, driving light and high-beam headlight
The exterior lights can be switched on and off at the lights operating facility.

Side lights
The side lights are activated by turning the light switch in the light control unit to "Position 1". When the side lights are switched on, the following lights are also activated:
- Dim daytime driving lights
- Tail lights on left and right
- Number-plate light on left and right
- Indicator lamp in the instrument cluster
- Left and right side marker light

To use the side lights to make the parked vehicle easier to identify in darkness, the light switch must be turned to "Position 1".When the side lights are switched on, an acoustic signal sounds if the driver's door is opened, while a Check Control message also appears in the instrument panel (KOMBI). Leaving the side lights on can drain the vehicle's battery.

LED principle of side lights
The side lights are activated by supplying white light-emitting diodes with pulse-width-modulated voltage. The LEDs are an element of the lighting ring. The light from the LEDs is fed into two ring-shaped fibre-optic conductors. The fibre-optic conductors allow the light to pass to the outside. The fibre-optic conductors have a lightly rippled surface on the rear side. This ripple effect ensures a homogeneous light distribution of the side lights.







Driving light
The light switch of the operating facility must be rotated to "Position 2" to activate the driving light. When the engine is switched off the side lights remain on, even if the light switch remains in "Position 2". When the driver's door is opened, the side lights are also switched off.
In "Position AUTO" the driving light is activated by the footwell module (FRM) based on information from the rain-light-solar-condensation sensor.
The headlights execute a reference run each time terminal 15 is activated. During the reference run, the adjustment range of the headlight beam throw adjustment and, depending on the equipment, the adaptive headlight are referenced.

High-beam headlight
The high-beam headlight is switched on under the following preconditions:
- "Terminal 15 on"
- Driving light on
- High-beam headlight selected at turn signal/high beam switch or with high-beam assistant activated

The headlight flasher is activated by pulling back the turn signal/high beam switch.

Bi-xenon headlights
Bi-xenon headlights are available as optional equipment in place of the standard halogen headlights. The bi-xenon light is located in the outer chamber of the bi xenon headlight.

The "high-beam headlight on" signal activates the cover on the driving light to expose the high-beam headlight section. The high-beam headlight is also used for the headlight flasher function.

Daytime driving lights
The daytime driving lights are LEDs. The daytime driving lights rely on components from the side lights assembly. However, the pulse width modulation is cancelled and the light-emitting diodes are supplied directly with full voltage from the vehicle voltage. This makes the daytime driving lights substantially brighter than the side lights. The light switch must be turned to "Position 0" before the daytime driving lights can be activated.
The daytime driving lights can also be activated by the automatic driving lights control when the rain-light-solar-condensation sensor indicates high-intensity ambient brightness. The light switch must be in its "AUTO Position". On national model versions with this feature, the daytime driving lights are activated when Terminal 15 is switched on. The daytime driving lights can be activated and deactivated in "Personal Profile". The daytime driving lights are switched off at "Terminal 15 off".
In the following national-market versions it is not possible to deactivate the daytime driving lights using the "Personal Profile" feature (encoded element):
- Canadian market version
- Russian market version
- Japanese national-market version

Welcome lights
When the vehicle is unlocked the side lights are switched on for approximately 20 seconds. This allows the vehicle to be identified more easily in unfavourable incident light.
Before the welcome lights can be activated the light switch must first be turned to "Position 2" or the "AUTO Position". The welcome lights are activated as soon as the vehicle's locks are disengaged. The Car Access System (CAS) supports this process by furnishing the status of the central locking system through K CAN2. The footwell module (FRM) receives the "unlock" status message and responds by switching on the exterior lights for approximately 20 seconds. While the welcome lights are on they can be deactivated again at any time with the status "Terminal 15 on".
The following lightings are activated:
- Tail lights
- Parking lamps
- Side marker light
- Interior lighting
- Courtesy lighting
- Licence plate lamps
- Indicator lamp in the instrument cluster

Headlight courtesy delay feature
The headlight courtesy delay feature belongs to the standard equipment. The turn signal/high beam switch can be used to switch on the headlight courtesy delay feature under the following preconditions:
- "Lights off"
- "Terminal 30 on"

To trigger headlight courtesy delay feature activate the headlight flashers one time. The switch-on time is set at 40 seconds at the factory, but can be adjusted to between 0 and 240 seconds using the "Personal Profile" feature. While the headlight courtesy delay feature is active the following lights remain on:
- Driving light
- Parking lamps
- Tail lights
- Licence plate lamps
- Indicator light
- Side marker light

Automatic driving lights control
The following preconditions must be satisfied before the driving light can be activated automatically:
- Light switch in "AUTO Position"
- "Terminal 15 on"
- Rain-light-solar-condensation sensor reports low brightness

The LIN bus provides the link between the rain-light-solar-condensation sensor and the Junction Box Electronics (JBE) module.
The junction box electronics (JBE) requests the status of the ambient brightness from the rain-light-solar-condensation sensor via the LIN bus.The rain-light-solar-condensation sensor relays this information to the Junction Box Electronics (JBE) module. The Junction Box Electronics (JBE) module transmits the status via K CAN2. The footwell module (FRM) receives the status of ambient brightness and analyses it. The footwell module (FRM) carries out any prompt received to switch the driving lights on or off. The automatic driving lights control switches on the driving light together with the side lights.
Should no signal be received from the rain-light-solar-condensation sensor owing to a defect while the automatic driving lights control is activated, the footwell module will respond by switching on the headlamps.
Once the headlamps have been switched on by the automatic driving lights control, they can be switched off again with the light switch or by the rain-light-solar-condensation sensor, provided that ambient lighting of adequate brightness is present. Even after "Terminal 15 off" the side lights can remain on because they were activated by the automatic driving lights control system. The side lights are switched off automatically when the driver's door is opened. When the occupants exit the vehicle from another door, the side lights are switched off when the vehicle's locks are engaged.
The footwell module (FRM) will only switch on the driving lights when there is low ambient brightness. There may thus be a delayed activation of the driving light when the vehicle enters a tunnel or a tree-shaded lane. The light switch must be in its "AUTO Position".

Adaptive Headlights
The Adaptive Headlight is available as optional equipment. The Adaptive Headlight is basically a bi xenon headlight that can tilt along a horizontal and vertical axis and is part of both the low-beam headlight and high-beam headlight function. The Adaptive Headlight feature allows the headlights to turn into the direction of the driving area while cornering. Using the automatic headlight beam throw adjustment ensures optimum adaptation in every driving situation. The headlights swivel angle is continuously adjusted for the duration of cornering. This enhanced illumination during cornering improves visibility for the driver.
The following preconditions must be satisfied before the Adaptive Headlight can be activated automatically:
- Light switch in "AUTO Position"
- "Terminal 15 on"

The enhanced illumination during cornering provides:
- Safe cornering with rapid recognition of potential obstacles
- improved perception of the immediate environment
- Preventing accidents

The Adaptive Headlight's electronics componentry facilitates rapid reaction to current driving situation. The system is controlled electronically and thus less susceptible to malfunctions than a purely mechanical system. The electronics can also activate an emergency program.