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Headlamp Control, Function - GF82.10-P-2009RDA

Model 172.4 

up to model year 2017 

with code 615 (Bi-xenon headlamps with active light function) 

with code 621 (Intelligent Light System (left-hand traffic)) 

with code 622 (Intelligent Light System) 

Function requirements, general 

Driving lights actuation, general 

Driving lights actuation includes all functions which serve the optimum illumination of the road while driving.

During driving lights actuation, the standing lights actuation is active; this is described in a separate document.

The driving lights actuation function is comprised of the following subfunctions:

IMPORTANT The driving lights are actuated corresponding to the position of the exterior lights switch (S1). The front SAM control unit with fuse and relay module (N10/1) reads in the status of the exterior lights switch directly (voltage-coded).

Additional function requirements for low beams actuation 

IMPORTANT The electronic ignition lock control unit (N73) sends the status of circuit 15 to the front SAM control unit over the interior CAN (CAN B).

Function sequence for low beam actuation 

Turning the exterior lights switch to the "Manual driving lights" position requests actuation of the low beams.

The front SAM control unit reads in the status of the exterior lights switch and actuates the left xenon light power supply module (E1n4) at the left front lamp unit (E1) and the right xenon light power supply module (E2n4) at the right front lamp unit (E2).

The front SAM control unit also transmits the request "Low beams indicator lamp On" via the interior CAN to the instrument cluster (A1), which then actuates the low beams indicator lamp (A1e67).

The left xenon light power supply module actuates the left xenon bulb with integral ignition module (E1e10) and the right xenon light power supply module actuates the right xenon bulb with integral ignition module (E2e10).

Once the xenon bulb has ignited, the respective xenon light power supply module controls the burning voltage of the xenon bulb.

Additional function requirements for high beam actuation 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 to the front SAM control unit over the interior CAN.

Function sequence for high beam actuation 

The high beam actuation function encompasses the following subfunctions:

Function sequence for high beams 

High beam actuation is requested by pushing the combination switch (S4) forward.

The steering column tube module control unit (N80) directly reads in the position of the combination switch and transmits it to the front SAM control unit via the chassis CAN (CAN E).

The front SAM control unit receives the switch position of the combination switch and uses this to generate the request "High beams On" and activates the high beams actuation.

High beams actuation in vehicles up to 31.05.2012:

The front SAM control unit actuates the following components in the front lamp units:

When the high beam solenoids are actuated, the covers that partially cover the light cones of the xenon bulbs are folded away, and the entire light beam is released for illuminating the road.

High beams actuation in vehicles as of 01.06.2012:

The front SAM control unit transmits the switch position of the combination switch via the front end CAN (CAN G) to the headlamp control unit (N71/1). The headlamp control unit then actuates the following components in the front lamp units over the headlamp LIN:

The rollers that partially cover the light cone of the xenon bulbs are turned away, and the entire light beam is therefore released for illuminating the road.

Additionally, the front SAM control unit transmits the "High beams On" request over the interior CAN to the instrument cluster, which then actuates the high beams 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 function, the combination switch must be pulled backward.

If the combination switch is pulled back and held, the high beam actuation is active for maximum t = 30 s. The permanently present request is then interpreted as a "stuck combination switch".

Since no separate high beams are installed to implement the headlamp flasher function, the xenon bulbs must be illuminated when low beams actuation is not active.

Additional function requirements for daytime running lights actuation 

Function sequence for daytime running lights actuation 

The instrument cluster sends the request "Daytime running lights On" depending on the country coding or if the daytime running lights request was manually activated in the menu "Settings", "Light" via interior CAN.

The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) sends the "engine running" or "drivetrain operational" signal over the chassis CAN.

The instrument cluster sends the vehicle speed over the interior CAN. The front SAM control unit reads in all relevant information, evaluates it and in vehicles without code 498 (Japan version) and without code 835 (South Korea vehicles additional parts) actuates the left daytime running lights headlamp (E1/3) and the right daytime running lights headlamp (E2/3) directly.

In vehicles with code 498 (Japan version), the front SAM control unit activates the low beams actuation, and the daytime running light headlamps are actuated as position lamps.

IMPORTANT

Model 172.4 up to model year 2017

with code 622 (Intelligent Light System)

with code 835 (Vehicles for South Korea, additional parts)

The daytime running light headlamps are installed, but are not actuated.

During darkness, the front SAM control unit actuates the daytime running light with reduced power and activates the low beam actuation.

The ambient brightness is recorded by the light sensor (B38/1) (without code 345 (Windshield wiper with rain sensor)) or the rain/light sensor (B38/2) (with code 345 (Windshield wiper with rain sensor)).

The front SAM control unit reads in the data from the light sensor or the rain/light sensor via the wiper/inside rearview mirror LIN (LIN 2).

The daytime running lights actuation is deactivated as soon as the exterior lights switch is turned to the "Standing lights", "Manual driving lights" or "Left parking light" or "Right parking light" position.

In vehicles with CODE 460 (Canada version), the daytime running light actuation is switched off after expiration of a time interval of t = 3 min when the vehicle is standing still.

When the vehicle then starts to move again, the front SAM control unit automatically activates daytime running lights actuation.

IMPORTANT The daytime running lights have a higher priority compared to the auto on/off driving lights.

In countries with legal daytime running light requirements, only the headlamp flasher is permissible but not the high beams.

The high beams are permissible only when the driving lights are manually switched on via the exterior lights switch (except CODE 460 (Canada version) or except CODE 494 (USA version)).

Additional function requirements for auto on/off driving lights 

Function sequence for auto on/off driving lights 

The auto on/off driving lights are no more than a convenience system and do not exempt the driver from following the rules of the road traffic regulations.

The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or the "Drivetrain operational" signal over the chassis CAN.

The instrument cluster sends the vehicle speed over the interior CAN.

The front SAM control unit reads in the status of the exterior lights switch directly and the data of the light sensor or rain/light sensor via the wiper/inside rearview mirror LIN.

In the auto on/off driving lights, the low beams are automatically switched on or off. This occurs depending on the ambient brightness or depending on the activities of the windshield wiper system:

Function sequence for auto on/off driving lights via light sensor or rain/light sensor 

The light sensor or the rain/light sensor evaluates the ambient brightness. The front SAM control unit reads in the data of the light sensor or the rain/light sensor via wiper/inside rearview mirror LIN and activates the low beams actuation if darkness is recognized.

Function sequence for auto on/off driving lights over wiper activities 

If the low beams are switched on or off due to the activities of the windshield wiper system, one refers to wiper, rain or adverse weather light. The front SAM control unit controls this function and evaluates the data of the rain/light sensor or the wipe request via the combination switch for this. 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.

IMPORTANT Switch-off conditions for auto on/off driving lights:

In the event of light sensor or rain/light sensor failure, the auto on/off driving lights 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 driving lights function remains switched on.

If the wiper startup suppression function is canceled, the auto on/off driving lights remain active for an additional t = 60 s.

Behavior of exterior lights when auto on/off driving lights activated    
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" signal or
"Drive train ready" signal set or v > 3 km/h		 On On (high beams permissible)
End of trip  Standing lamp  Low beam 
"Engine running" signal or
"Drive train ready" signal set or v > 3 km/h		 On On (high beams permissible)
Terminal 15 ON On Off
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

Additional function requirements for automatic headlamp range adjustment 

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 CDI control unit or the ME-SFI control unit transmits the "Engine running" or "Drivetrain operational" signal (set) via the chassis CAN, the front SAM control unit and the front end CAN to the headlamp control unit.

In order to determine the current vehicle level in vehicles without code 483 (ADVANCED AGILITY package), the voltage signals of the left rear level sensor (B22/7) and left front level sensor (B22/8) are read in directly by the headlamp control unit.

In vehicles with code 483 (ADVANCED AGILITY package), the voltage signals of the following sensors are recorded by the adaptive damping system control unit (N51/5) and transmitted via the chassis CAN, the front SAM control unit and front end CAN to the headlamp control unit:

IMPORTANT Zero-point programming is performed at the end of production to compensate for suspension tolerances. With successful programming, visual feedback occurs through the movement of the headlamp units "center-down-up-center".

If the vehicle is moving at a constant speed, the automatic headlamp range adjustment system operates in "static mode" at a slow adjustment rate.

When the vehicle is accelerated, the "dynamic mode" is activated and the reaction time of the system is reduced sharply. The "dynamic mode" is activated depending on the amount of speed change and additional signals such as the brake pedal and the accelerator pedal positions.

IMPORTANT When the vehicle is standing automatic headlamp range adjustment is accomplished in the "dynamic mode".

Information about wheel speeds and wheel rotation directions as indicators of the vehicle speed are transmitted by the Electronic Stability Program control unit (N30/4) via the chassis CAN, the front SAM control unit and the front end CAN to the headlamp control unit.

The headlamp control unit receives this information, evaluates it and actuates the left headlamp range adjustment actuator motor (E1m1) via the left headlamp LIN (LIN G1) and the right headlamp range adjustment actuator motor (E2m1) via the right headlamp LIN (LIN G2) accordingly.

  Electrical function schematic for driving lights actuation   PE82.10-P-2059-97TAB
  Overview of exterior lights system components   GF82.10-P-9998RD 
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