LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 2017 >> GLS450 >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Electrical System - Body - 166 Chassis 1 Of 8 >> Basic Knowledge >> Headlamp Control, Function >> (Headlamp Control, Function - GF82.10-P-2009GRA)

(Headlamp Control, Function - GF82.10-P-2009GRA)

Model 166 

up to Model year 2016 

with CODE 615 (Bi-xenon headlamp unit with integrated curve illumination) 

Model 166 

up to Model year 2016 

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

Model 166 

up to Model year 2016 

with CODE 622 (Intelligent Light System (right-hand traffic)) 

Function requirements, general 

Driving lights actuation, general 

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

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 SAM control unit (N10) reads in the status of the exterior lights switch directly.

Additional function requirements for low beams actuation 

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

IMPORTANT The standing lights are active during low beams actuation. The standing lights actuation is described in the separate document "Standing/parking lights actuation function".

Function sequence for low beam actuation 

Turning the exterior lights switch to the "Manual driving lights" position requests actuation of the low beams. The SAM control unit directly reads in the status of the exterior lights switch, actuates the left xenon light power supply module (E1n4) in the left front lamp unit (E1) and the right xenon light power supply module (E2n4) in the right front lamp unit (E2) directly and sends the "Low beams indicator lamp ON" request via interior CAN to the instrument cluster (A1).

The left xenon light power supply module actuates the left xenon bulb with integrated ignition module (E1e10).

The right xenon light power supply module actuates the right xenon bulb with integrated ignition module (E2e10).

Once the xenon bulbs have ignited, the respective xenon light power supply module actuates the burning voltage of the xenon bulb.

The instrument cluster actuates the low beams indicator lamp (A1e67).

Additional function requirements for high beam actuation 

IMPORTANT The electronic ignition lock control unit transmits the circuit 15 status via the interior CAN to the SAM control unit.

Function sequence for high beam actuation 

The high beams actuation function comprises 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 switch position of the combination switch and sends this via chassis CAN 1 (CAN E1), electronic ignition lock control unit and interior CAN to the SAM control unit and via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 (CAN E2) to the headlamp control unit (N71/1).

The headlamp control unit receives the switch position of the combination switch and actuates the left light distribution actuator motor (E1m3) over the left headlamp-LIN (LIN G1) and the right light distribution actuator motor (E2m3) over the right headlamp-LIN (LIN G2). The position of the covers, which partially block the light cones of the xenon bulbs, is changed accordingly, whereupon the entire light beam is then released for illuminating the road surface.

The SAM control unit then transmits the "High beams ON" status over the interior CAN to the instrument cluster, which 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 function, the combination switch must be pulled backward. 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.

IMPORTANT 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".

Additional function requirements for daytime running lights actuation 

Function sequence for daytime running lights actuation 

The instrument cluster transmits the "Daytime running lights ON" request depending on the national coding or manually via the "Settings", "Lights" menu via the interior CAN to the front SAM control unit.

The CDI control unit (N3/9) (diesel engine) or the ME-SFI [ME] control unit (N3/10) (gasoline engine) sends the "Engine running" or "Drive train operational" signal over the chassis CAN 1, electronic ignition lock control unit and the interior CAN to the SAM control unit.

The vehicle speed is calculated on the basis of the wheel speeds. For this, the Electronic Stability Program control unit (N30/4) sends the corresponding data via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 (CAN E2) to the instrument cluster. The instrument cluster calculates the vehicle speed and sends this to the SAM control unit over interior CAN.

The SAM control unit reads in all relevant information, evaluates it and actuates the left daytime running lights headlamp (E1/3) and right daytime running lights headlamp (E2/3) on vehicles except CODE 498 (Japan version). In vehicles with CODE 498 (Japan version), the low beams are actuated to output the daytime running lights function; the daytime running light headlamps are only used as position lamps.

In darkness, the SAM control unit activates the low beams actuation and actuates the daytime running lights headlamps with reduced power.

IMPORTANT The low beams actuation is described in more detail in the chapter "Low beams actuation".

The ambient brightness is recorded by the rain/light sensor (B38/2). The SAM control unit reads in the signals of the rain/light sensor (dimness stage) over the roof LIN (LIN B13).

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.

On vehicles with CODE 460 (Canada version), the daytime running lights actuation is switched off after t = 3 min with the vehicle at a standstill. When the vehicle then starts to move again, the SAM control unit automatically activates daytime running lights actuation.

IMPORTANT The daytime running lights actuation has 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 and except CODE 494 (USA version)).

Additional function requirements for auto on/off driving lights 

IMPORTANT The CDI control unit or the ME-SFI [ME] control unit transmits the "Engine running" or "Drive train operational" signal via chassis CAN 1, the electronic ignition lock control unit and the interior CAN to the SAM control unit.

The instrument cluster transmits the vehicle speed to the SAM control unit via the interior CAN.

The SAM control unit reads in the status of the exterior lights switch directly.

Function sequence for auto on/off driving lights 

In the auto on/off driving lights, the low beams are automatically switched on or off.

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.

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)
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 windshield wiper system:

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

The rain/light sensor evaluates the ambient brightness. The SAM control unit reads in the signals of the rain/light sensor via roof LIN and activates the low beams actuation if darkness is recognized.

IMPORTANT In the event of any 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.

Function sequence for auto on/off driving lights through windshield 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 SAM control unit controls the windshield wiper system and evaluates the signals from 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 SAM control unit activates low beams actuation. If there are no wipe cycles for t ≥ 60 s, low beams actuation is deactivated.

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

Additional function requirements, automatic HRA [LWR] 

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.

To determine the vehicle level at any given moment, on vehicles except CODE 489 (AIRMATIC (air suspension with level adjustment and adaptive damping system ADS)) the voltage signals of the right front level sensor (B22/9) and the right rear level sensor (B22/10) are read in directly by the headlamp control unit.

On vehicles with CODE 489 (AIRMATIC (air suspension with level adjustment and adaptive damping system ADS)), the AIRMATIC control unit (N51/3) sends the voltage signals of the following sensors over the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the headlamp control unit:

IMPORTANT Zero-point programming is performed at the end of production to compensate for suspension tolerances.

Successful programming is confirmed by visual feedback by the motion sequence of the headlamps "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 automatic headlamp range adjustment is significantly reduced. 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 on wheel speeds, as indicators of vehicle speed, is sent by the Electronic Stability Program control unit over chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the headlamp control unit.

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

The left headlamp range adjustment actuator motor moves the headlamp unit in the left front lamp unit.

The right headlamp range adjustment actuator motor moves the headlamp unit in the right front lamp unit.

  Electrical function schematic for driving lights actuation   PE82.10-P-2059-97NAB
  Overview of exterior lights system components   GF82.10-P-9998GR 
scientia non olet · About LEMON Manuals