Headlamp control, function - GF82.10-P-2009GVB
MODEL 251.0/1 as of model year 2009 up to model year 2011 with CODE 615 (Bi-xenon headlamp unit with integrated curve illumination)
MODEL 251.0/1 as of model year 2009 up to model year 2011 with CODE 616 (Bi-xenon headlamp unit with integrated asymmetric curve illumination)
MODEL 251.0/1 as of model year 2011 with CODE 614 (Bi-xenon headlamp unit)
MODEL 251.0/1 as of model year 2011 with CODE 618 (Bi-xenon headlamps)
Function requirements for driving lights actuation, general
- No overvoltage or undervoltage (operating voltage range U ≥ 7 ≤ 17.5 V)
Driving lights actuation, general
Driving lights actuation includes all functions which serve the optimum illumination of the road while driving.
The driving lights are actuated corresponding to the position of the rotary light switch (S1).
During driving lights actuation, the standing lights actuation is active; this is described in the separate "Standing/parking lights actuation, function" Service Information.
The driving lights actuation function is comprised of the following subfunctions:
- Function sequence for low beam actuation
- Function sequence for high beam actuation
- Function sequence for daytime running lights actuation
- Auto on/off headlamps function sequence
- Function sequence for headlamp range adjustment (HRA [LWR])
Additional function requirements for low beams actuation
- Terminal 15 ON
The EZS control unit (N73) sends the status of circuit 15 via interior CAN (CAN B) to the front SAM control unit (N10).
Function sequence for low beam actuation
The upper control panel control unit (N72/1) reads in the status of the rotary light switch via the instrument panel LIN (LIN 1) and transmits this via interior CAN to the front SAM control unit.
Vehicles up to 31.7.10:
The front SAM control unit receives all the relevant information and directly actuates the xenon headlamp supply module (E1n4) in the left front lamp unit (E1) and the xenon headlamp supply module (E2n4) in the right front lamp unit (E2).
The xenon headlamp supply module at the left front lamp unit actuates the xenon headlamp ignition module (E1n2) and thus the left low beam (E1e2). The xenon headlamp supply module at the right front lamp unit actuates the xenon headlamp ignition module (E2n2) and thus the right low beam (E2e2).
Vehicles as of 1.8.10:
The front SAM control unit receives all the relevant information and forwards the "Switch low beams on" request as a voltage signal directly to the xenon headlamp control unit (E1n1) at the left front lamp unit and the xenon headlamp control unit (E2n1) at the right front lamp unit.
The xenon headlamp control unit at the left front lamp unit then actuates the left bi-xenon light with integrated ignition module (E1e10). The xenon headlamp control unit on the right front lamp unit then actuates the right
bi-xenon light with integrated ignition module (E2e10). In addition, the front SAM control unit sends the request "Low beams indicator lamp On" via interior CAN to the instrument cluster (A1), which then actuates the low beams indicator lamp (A1e67).
Additional function requirements for high beam actuation
- For high beams function: Circuit 15R and low beams On
- For headlamp flasher function: Circuit 15R On
The EZS control unit sends the status of circuit 15 via interior CAN to the front SAM control unit.
Function sequence for high beam actuation
The high beams actuation is comprised of the following subfunctions:
- Function sequence for high beams
- Function sequence for headlamp flasher
Function sequence for high beams
The high beam actuation is requested by pressing the combination switch (S4) forward.
The steering column tube module (N80) directly reads in the switch position of the combination switch and transmits this via engine compartment CAN (CAN C), central gateway control unit (N93) and interior CAN to the front SAM control unit.
The front SAM control unit receives all the relevant information and directly actuates the left high beam (E1e1) (up to 31.7.10) and the right high beam (E2e1) (up to 31.7.10) as well as the left high beam solenoid (E1l1) and the right high beam solenoid (E2l1). The panels which partially cover up the bi-xenon light cone, are folded away thereby releasing the entire light beam to illuminate the traffic lane. The front SAM control unit then transmits the "High beam actuation active" status via the interior CAN to the instrument cluster. This then actuates the high beam indicator lamp (A1e3).
Function sequence for headlamp flasher
The function sequence and signal path for the headlamp flasher function correspond to that of the high beam function.
However, to request the headlamp flasher, the combination switch must be pulled backward. The high beams actuation remains active for as long as the combination switch is held in this position.
When the low beams actuation is not active on vehicles up to 31.7.10, only the high beams are actuated as turning on the bi-xenon lights would take too long because of the ramp-up up to full brightness.
Vehicles as of 1.8.10 are not equipped with any additional high beams. Here, low beam actuation is activated and the bi-xenon lights ignited.
On vehicles up to 31.7.10 with code (460) Canada version or code (494) USA version, the high beams must not be actuated at the same time as the left fog lamp (E5/1) and the right fog lamp (E5/2). The last incoming request has priority.
Additional function requirements for daytime running lights actuation
- Engine running (n > 300 rpm) or circuit 61 On or vehicle speed v > 3 km/h
- "Permanent" function activated in the "Settings", "Illumination", "Driving lights circuit" menu in the instrument cluster (except vehicles with code (460) Canada version)
- Rotary light switch in position:
- Exterior lights OFF "0"
- Auto on/off headlamps "AUTO"
- "Left parking light" or "Right parking light" (can be coded)
The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) sends the engine speed and the status of circuit 61 via engine compartment CAN, central gateway control unit and interior CAN to the front SAM control unit.
The instrument cluster sends the vehicle speed to the front SAM control unit over the interior CAN.
The upper control panel control unit reads in the status of the rotary light switch over the instrument panel LIN and sends it over the interior CAN to the front SAM control unit.
Function sequence for daytime running lights actuation
The request for the daytime running lights function is output depending on the country coding or activated manually by the instrument cluster on the interior CAN.
Vehicles up to 31.7.10:
The front SAM control unit reads in all of the relevant information, evaluates it, and actuates the xenon headlamp supply modules. The xenon headlamp supply modules then actuate the xenon headlamp ignition modules and thereby the low beams.
In vehicles with code (460) Canada version or code (494) USA version, low beam actuation is activated in accordance with the ambient brightness. This is detected by the rain/light sensor (B38/2). The overhead control panel control unit (N70) reads in the signals of the rain/light sensor directly and forwards these via interior CAN to the front SAM control unit. If it is dark, the front SAM control unit activates both low beam actuation and standing lights actuation. Only low beam actuation takes place during daylight.
Vehicles as of 1.8.10:
The front SAM control unit reads in all of the relevant information, evaluates this and actuates the left daytime running lights headlamp (E1/3) and the right daytime running lights headlamp (E2/3).
When it is dark and the rotary light switch is in the "AUTO" position, the front SAM control unit actuates the daytime running lights headlamps at reduced power and also switches on the low beam actuation.
For vehicles with code (460) Canada version or code (494) USA version, the daytime running lights headlamps are switched on in darkness while undimmed. For vehicles with code (498) Japan version, the daytime running lights headlamps are used as position lamps. They are not actuated as for the daytime running lights. The daytime running lights headlamps are only switched on in the dark in addition to the low beam actuation.
For vehicles with code (460) Canada version or code (494) USA version, daytime running lights actuation is switched off when the vehicle is stationary after t = 3 min. When the vehicle then starts to move again, the front SAM control unit automatically activates daytime running lights actuation.
Daytime running lights actuation is deactivated as soon as the rotary light switch is moved to the "Standing lights" position or the "Manual driving lights" position.
The daytime running lights function has a higher priority than the auto on/off headlamps function. In countries with legal daytime running lights specification only the headlamp flasher is permissible but not the high beams. The high beams are only permissible when the driving lights are switched on manually (not with code (460) Canada version or code (494) USA version).
Additional function requirements for auto on/off headlamps
- Engine running (n > 300 rpm) or circuit 61 On or vehicle speed v > 3 km/h
- Rotary light switch in "AUTO" position
The CDI control unit or the ME-SFI [ME] control unit sends the engine speed or the status of circuit 61 via engine compartment CAN, central gateway control unit and interior CAN to the front SAM control unit.
The instrument cluster sends the vehicle speed to the front SAM control unit over the interior CAN.
The upper control panel control unit reads in the status of the rotary light switch over the instrument panel LIN and sends it over the interior CAN to the front SAM control unit.
Auto on/off headlamps function sequence
With the auto on/off headlamps, the low beams are automatically switched on or off.
The auto on/off headlamps function is no more than a comfort function and does not exempt the driver from following the rules in the road traffic regulations.
| Behavior of exterior lights with active auto on/off headlamps: | ||
| Start of trip | Standing lamp | Low beam |
| Circuit 15C OFF | Off | Off |
| Circuit 15C ON | Off | Off |
| Circuit 15R ON | On | Off |
| Terminal 15 ON | On | Off |
| Engine running (n > 300 rpm) or circuit 61 On or vehicle speed v > 3 km/h | On | On (high beams permissible) |
| End of trip | Standing lamp | Low beam |
| Engine running (n > 300 rpm) or circuit 61 On or vehicle speed v > 3 km/h | On | On (high beams permissible) |
| Circuit 15R ON | On | Off |
| Circuit 15C ON (driver door closed) | On | Off |
| Circuit 15C ON (driver door open) | Off | Off |
| Circuit 15C OFF | Off | Off |
The low beams are switched on or off depending on the ambient brightness or depending on the activities of the wiper system:
- Function sequence for auto on/off headlamps over rain/light sensor
- Function sequence for auto on/off headlamps via wiper activities
Function sequence for auto on/off headlamps over rain/light sensor
The ambient brightness is sensed by the rain/light sensor. The overhead control panel control unit reads in the signals of the rain/light sensor directly and forwards these via interior CAN to the front SAM control unit. The front SAM control unit activates low beam actuation when it is dark.
In the event of rain/light sensor failure, the auto on/off headlamps are not deactivated until the engine is switched off. When the vehicle is being driven through a tunnel and if the wiper start suppression function is active, the auto on/off headlamps function remains switched on.
Function sequence for auto on/off headlamps via wiper activities
If the low beams are switched on or off due to the activities of the wiper system, one refers to adverse weather light. The front SAM control unit actuates the wiper system.
If the windshield wiper system is activated for t ≥ 20 s with a wipe cycle time of t < 6 s, the front SAM control unit activates low beam actuation. If there are no wipe cycles for t ≥ 60 s, low beams actuation is deactivated.
If the wiper start suppression function is canceled, the auto on/off headlamps remain active for an additional t = 60 s.
Additional function requirements for automatic headlamp range adjustment
- Circuit 61 ON
- Driving lights On (low beam/high beam)
The CDI control unit or the ME-SFI [ME] control unit sends the status of circuit 61 via engine compartment CAN to the instrument cluster. The instrument cluster sends the "Circuit 61 decoupled" signal to the headlamp range adjustment control unit (N71) (up to 31.7.10) or to the xenon headlamp control unit (as of 1.8.10) at the left front lamp unit.
Function sequence for automatic HRA [LWR]
The automatic HRA [LWR] permits the correction of the headlamp range of the vehicle headlamps as a function of the load or the vehicle pitch motions induced by the vehicle dynamics.
The following information that describes the driving status is included into the computation of the correction values:
- Body pitch angle from the axis positions
- Vehicle speed in order to calculate the operating mode
This information is required to regulate the adjustment rate of the automatic headlamp range adjustment.
If the vehicle is moving at a constant speed, the automatic headlamp range adjustment system operates in "static mode" at a slow adjustment rate. In the event of acceleration, the "dynamic mode" is activated with a high adjustment rate.
This information is read in and evaluated on vehicles up to 31.7.10 by the headlamp range adjustment control unit and on vehicles as of 1.8.10 by the xenon headlamp control unit at the left front lamp unit.
The body pitch angle from the axle locations is recorded by the following components:
- Vehicles without code (488) Steel/air suspension and without code (489) AIRmatic (air suspension with level adjustment and adaptive damping system ADS):
- Right front level sensor (B22/9) (front axle level) (read in directly)
- Right rear level sensor (B22/10) (rear axle level) (read in directly)
- Vehicles with code (488) Steel/air suspension:
- Right front level sensor (front axle level) (read in directly)
- Rear axle level control system control unit (N97) (rear axle level) (sent via engine compartment CAN)
- Vehicles with code (489) AIRmatic (air suspension with level adjustment and adaptive damping system ADS):
- AIRmatic with ADS control unit (N51) (front axle level and rear axle level) (sent via engine compartment)
The headlamp range adjustment control unit (up to 31.7.10) or the xenon headlamp control unit on the left front lamp unit (as of 1.8.10) reads in all relevant information and uses it to calculate the vehicle level.
Information on wheel speeds and wheel rotation directions as an indicator of vehicle speed is sent by the ESP control unit (N47-5) via engine compartment CAN to the headlamp range adjustment control unit (up to 31.7.10) or to the xenon headlamp control unit at the left front lamp unit (as of 1.8.10). This information is required to regulate the adjustment rate of the automatic headlamp range adjustment.
If the vehicle is moving at a constant speed, the automatic headlamp range adjustment system operates in "static mode" at a slow adjustment rate. In the event of acceleration, the "dynamic mode" is activated with a high adjustment rate.
Vehicles up to 31.7.10:
The headlamp range adjustment control unit reads in all relevant information via the engine compartment CAN, evaluates it and actuates the HRA [LWR] power module (E1n3) at the left front lamp unit and the HRA [LWR] power module (E2n3) at the right front lamp unit. The HRA [LWR] power modules then actuate the left headlamp range adjustment motor (E1m1) and the right headlamp range adjustment motor (E2m1) accordingly.
Vehicles as of 1.8.10:
The xenon headlamp control unit on the left front lamp unit reads in all the relevant information over the engine compartment CAN, evaluates it and sends corresponding correction values over the engine compartment CAN to the xenon headlamp control unit on the right front lamp unit.
The xenon headlamp control unit at the left front lamp unit actuates the left headlamp range adjustment motor and the xenon headlamp control unit at the right front lamp unit actuates the right headlamp range adjustment motor accordingly.
| Electrical function schematic for driving lights actuation | MODEL 251.0/1 as of model year 2009 up to model year 2011 with CODE 615 (Bi-xenon headlamp unit with integrated curve illumination) MODEL 251.0/1 as of model year 2009 up to model year 2011 with CODE 616 (Bi-xenon headlamp unit with integrated asymmetric curve illumination) | PE82.10-P-2059-97RAB | |
| MODEL 251.0/1 as of model year 2011 with CODE 614 (Bi-xenon headlamp unit) MODEL 251.0/1 as of model year 2011 with CODE 618 (Bi-xenon headlamps) | PE82.10-P-2059-97RAC | ||
| Overview of exterior lights system components | GF82.10-P-9998GM |