Operation CHARM: Car repair manuals for everyone.
Home >> Mercedes Benz >> 2009 >> C 350 (204.056) V6-3.5L (272.961) >> Repair and Diagnosis >> Lighting and Horns >> Fog/Driving Lamp >> Description and Operation >> GF82.10-P-3050CE Additional Functions For Driving Lights Actuation, Function >> Part 2

Part 2




Function sequence for active light distribution (With code (621) Intelligent Light System (left-hand traffic) or code (622) Intelligent Light System (right-hand traffic) or code (608) Adaptive Highbeam Assist)
Active light distribution encompasses the following subfunctions:
^ Function sequence for freeway lights
^ Function sequence for extended fog light
^ Function sequence, adaptive high beams (with code (608) Adaptive Highbeam Assist)
The functions are described using a left-hand drive vehicle as an example.

Additional function requirements for freeway lights
^ Function "Intell. Light System": activated in the "Settings", "Lights" menu in the instrument cluster
^ Extended fog light function inactive
^ Radius of curve r greater than or equal to 800 m

Function sequence for freeway lights
The freeway lights improve the illumination of the road by increasing the range of the low beams without blinding the preceding traffic.
This function is achieved by means of vertically deflecting the light cone and increasing the light output.
The freeway lights are activated at speeds typical for the freeway or expressway.
The freeway lights function is deactivated when it is raining.
Rain detection takes place by evaluating the windshield wiper signal (windshield wiper not in park position).
If the windshield wiper is in the park position for less than t = 600 ms, this is evaluated as continuous wiping. Rain is detected if the continuous wipe function is active for t > 2 min.





Schematic of light distribution for active freeway lights function
A Low beams light cone
D Freeway lights light cone

The freeway lights function depends on the following control factors:
- Steering wheel angle
- Vehicle speed
- Yaw characteristics of the vehicle
The selection of the function is made through the controls in the instrument cluster. The instrument cluster sends the corresponding status over the chassis CAN.
The steering column tube module control unit sends data for the steering angle sensor and the Electronic Stability Program control unit sends information on vehicle motion over the chassis CAN.
The instrument cluster sends the vehicle speed over the chassis CAN.
The front SAM control unit receives all relevant information and transmits it to the xenon light control units or the headlamp control unit over the front end CAN.
Starting at a vehicle speed of v = 90 km/h and a curve radius of r > 800 m for a driving distance of more than s = 2.5 km, the light output of the left xenon bulb with integrated ignition module (E1e10) and the right xenon bulb with integrated ignition module (E2e10) is increased linearly up to P = 38 W by the corresponding xenon light control unit or the headlamp control unit.
Model 204.0/2 up to 28.2.11, model 204.9:
Starting at a vehicle speed of v = 110 km/h and a curve radius of r > 800 m for a driving distance of more than s = 1 km the left xenon light control unit also actuates the left headlamp range adjustment actuator motor (E1m1).
The headlamp unit of the left front lamp unit is raised and thereby the range of the low beams increased. The maximum lift is reached at v = 130 km/h.
If the vehicle speed drops down to below v = 80 km/h, the "freeway lights" function is disabled.
Model 204.0/2 as of 1.3.11, model 204.3:
Starting at a vehicle speed of v = 110 km/h and a curve radius of r > 800 m for a driving distance of more than s = 1 km, the headlamp control unit actuates the left light distribution actuator motor (E1m3) over the left headlamp-LIN.
The position of the cover which partially covers up the xenon bulb light cone is changed accordingly thereby increasing the range of the low beams. Maximum release of the xenon lamp light cone is reached at v = 130 km/h.
If the vehicle speed drops down to below v = 80 km/h, the "freeway lights" function is disabled.
The position of the light distribution actuator motors at any given time and any faults that occur, such as short circuits or open circuits, are reported back to the headlamp control unit.

Additional function requirements for extended fog light function
^ Function "Intell. Light System": activated in the "Settings", "Lights" menu in the instrument cluster
^ Rear fog lights actuation active

Extended fog light function sequence
The extended fog light function improves the illumination of the edges of the road and reduces the internal dazzling.
It is activated at speeds typical of urban traffic and rural roads.
The xenon bulb light cone in the front lamp unit facing the inside of the road is raised and swiveled outwards at vehicle speeds below v = 70 km/h.





Schematic of light distribution for active extended fog light function
A Low beams light cone
E Extended fog light function light cone

The selection of the function is made through the controls in the instrument cluster. The instrument cluster then sends the corresponding status and the vehicle speed over the chassis CAN.
Model 204.0/2 up to 28.2.11, model 204.9:
The headlamp unit of the front lamp unit facing the inside of the road is raised and swiveled outwards through a = 8°.
Internal dazzling is reduced and illumination of the road surface at the side is improved.
The left xenon light control unit then actuates the left headlamp range adjustment actuator motor and the left active curve light actuator motor directly.
Model 204.0/2 as of 1.3.11, model 204.3:
The headlamp unit of the lamp unit facing the inside of the road is swiveled outwards through a = 8° changing the light distribution of the low beams.
The headlamp control unit then actuates the left active curve lights actuator motor and the left light distribution actuator motor over the left headlamp LIN.
Through actuation of the left light distribution actuator motor the part of the light-dark boundary that slopes to the right is covered.
Internal dazzling is reduced and illumination of the road surface at the side is improved.
If the "extended fog light function" is active, the "dynamic curve illumination" function is deactivated.
If during the extended fog light function, the high beams function is requested, the position of the headlamp unit is retained.
In vehicles as of 1.12.09 the left daytime running lights headlamp (E1/3) and the right daytime running lights headlamp (E2/3) are switched off because of the risk of possible internal dazzling.
The extended fog light function is deactivated under the following conditions:
- Failure of a lamp unit (low beam)
- Actuator motor malfunction
When testing and adjusting the front lamp unit, ensure that the extended fog light function is not active.

Additional function requirements for adaptive high beams (with code (608) Adaptive Highbeam Assist)
^ Function activated via the instrument cluster
^ Combination switch in "High beams" position
^ Exterior lights switch (S1) in position "A"
^ Vehicle speed v > 40 km/h
^ Multifunction camera signals "Darkness detected"

Function sequence for adaptive high beams (with code (608) Adaptive Highbeam Assist)
The adaptive high beams function is an assistance function.
The headlamp range of the driving lights is adapted to the distance of the nearest preceding or oncoming road user by means of actuation of various actuators in the front lamp units.
If no road users are detected, the adaptive high beams function automatically activates the high beams.





A Low beams light cone (approx. s = 65 m)
F Low beams light cone with optical headlamp range adjustment (maximum s = 300 m)
G Automatic high beams light cone

The selection of the function is made through the controls in the instrument cluster. The instrument cluster transmits the corresponding status via interior CAN to the front SAM control unit.
The steering column tube module control unit sends the position of the combination switch over the chassis CAN to the front SAM control unit.
The front SAM control unit reads in the status of the exterior lights switch.
After evaluating all function requirements, the front SAM control unit sends the enabling of the adaptive high beams function via chassis CAN to the multifunction camera.
The activated adaptive high beams function is shown on the instrument cluster by means of a symbol in the travel distance display (A1p7) (model 204.0/2/3/9 (except 204.077/277/377) without code (442) Comfort multifunction steering wheel) or in the multifunction display (A1p13) (with code (442) Comfort multifunction steering wheel, model 204.077/277/377). The front SAM control unit sends the "Adaptive high beams active" status via interior CAN to the instrument cluster for this.
The multifunction camera also evaluates the following information, among other things, to implement the adaptive high beams function:
- Steering wheel angle and steering wheel velocity
- Vehicle speed (wheel speed signals)
- Vehicle yaw behavior (vehicle movement)
The steering angle sensor data are sent by the steering column tube module control unit and information on the wheel speeds and wheel rotation directions as indicators of vehicle speed and vehicle yaw characteristics, is sent by the Electronic Stability Program control unit over the chassis CAN to the multifunction camera.
The traffic and environment situation in front of the vehicle is detected by the multifunction camera and accordingly evaluated.
Activation of the actuators installed in the front lamp units ensures the best possible illumination of the roadway without generating any dazzling effect for other road users.
The multifunction camera uses the brightness, shape, structure, color, where applicable, and motion of detected objects to differentiate between preceding or oncoming road users, street lighting, signs or other parts of the infrastructure.
The picture recognition module integrated into the multifunction camera judges the distance to the other road users, evaluates the outside brightness level of the vehicle environment and recognizes extreme weather conditions (e.g. thick fog, heavy snowfall) or tunnels.
A distinction is made between the following functions states:
- Optical headlamp range adjustment
- Automatic high beams
Optical headlamp range adjustment:
Depending on the distance of the vehicle to other road users and the geometry of the road (differences in height, angle), the multifunction camera sends the "Optical headlamp range adjustment" request via chassis CAN, front SAM control unit and front end CAN to the headlamp control unit.
The headlamp control unit then actuates the left headlamp range adjustment actuator motor over the left headlamp LIN and the right headlamp range adjustment actuator motor (E2m1) over the right headlamp LIN.
The headlamp units of the front lamp units are raised accordingly.
The road surface is better illuminated without causing a dazzling effect for other road users.
The light cone of the xenon light varies between s = 65 m (standard lighting) and s = 300 m.
If the vehicle speed sinks below v = 40 km/h, the "Optical headlamp range adjustment" is deactivated.
Automatic high beams:
The xenon bulb light cones are not fully released until vehicle speed is greater than v = 55 km/h and no other road users are detected. To this end, the headlamp control unit actuates the left light distribution actuator motor over the left headlamp-LIN and the right light distribution actuator motor (E2m3) over the right headlamp-LIN. The rollers which partially cover up the xenon bulb's light cone, are turned thereby uncovering the entire light beam to illuminate the traffic lane.
The multifunction camera sends the request for this via chassis CAN, front SAM control unit and front end CAN to the headlamp control unit.
If the vehicle speed sinks below v = 45 km/h, the automatic high beams are deactivated.
The activation or deactivation speed of the automatic high beams is controlled adaptively by the multifunction camera.
As soon as the automatic high beams are activated, the high beams indicator lamp (A1e3) in the instrument cluster lights up.
On roads with street lamps positioned regularly, the automatic high beams are deactivated.
Limits of the adaptive high beams:
In tight curves, the multifunction camera may not recognize oncoming vehicles or only do so very late due to the recording angle (= 35°).
The automatic high beams are deactivated depending on the steering angle.
On streets with structural separation (e.g. guardrails on freeways) the headlamps of oncoming vehicles are often concealed. These vehicles are not recognized by the multifunction camera. The automatic high beams are not switched off.
Due to the geometry of the structural separation and the location of the headlamps on cars, the drivers of the oncoming cars are not dazzled. Truck drivers, however, are dazzled due to the high seat position. The clearance lamps on trucks are not sufficient for recognition.
When driving over crests, oncoming vehicles are not recognized until late and the automatic high beams are therefore also switched off later. In this situation, however, the driver of the oncoming vehicle is also dazzled by the low beams.
Lights that are visible for a long time and that slowly become brighter (e.g. with partial concealment of the headlamps by trees) make it more difficult to recognize oncoming vehicles.
With bright lights that appear suddenly (e.g. street lamps, traffic lights, lot illumination), the automatic high beams are deactivated.
Some reflectors cannot be clearly differentiated by road users (e.g. motorcyclists). The automatic high beams are deactivated because of the existing danger of dazzling other road users.




pro multis · About Operation CHARM