Headlamp Control, Function - GF82.10-P-2009RDN
Model 172.4
as of model year 2017
with code 640 (High-performance LED)
with code 641 (Headlamps, LED, dynamic, left-side traffic)
with code 642 (Headlamps, LED, dynamic, right-side traffic)
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. During driving lights actuation, the standing lights actuation is active; this is described in a separate document.
The driving lights actuation encompasses the following subfunctions:
- Function sequence for low beam actuation
- Function sequence for high beam actuation
- Function sequence for daytime running lights actuation
- Function sequence for auto on/off driving lights
- Function sequence for automatic headlamp range adjustment (HRA [LWR])
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
- Circuit 15 ON
The electronic ignition lock control unit (N73) transmits the circuit status of circuit 15 to the front SAM control unit via 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 directly and sends the "Low beams ON" request via chassis CAN 2 (CAN E2) to the left headlamp control unit (E1n9) and the right headlamp control unit (E2n9).
The left headlamp control unit via the left headlamp-LIN (LIN G1) and the left front actuation module, LED exterior lights (E1n7) actuates the left low beam (close range) (E1e15) and the left low beam (long range) and high beams (E1e16) in the left front lamp unit (E1).
The right headlamp control unit via the right headlamp-LIN (LIN G2) and the right front actuation module, LED exterior lights (E2n7) actuates the right low beam (close range) (E2e15) and the right low beam (long range) and high beams (E2e16) in the right front lamp unit (E2).
The front SAM control unit also sends the "low beams indicator lamp ON" request over the interior CAN to the instrument cluster (A1).
The instrument cluster actuates the low beams indicator lamp (A1e67).
Additional function requirements for high beam actuation
- For high beams function: Circuit 15 and low beams On
- For headlamp flasher function: Terminal 15R On
The electronic ignition lock control unit sends the status of circuit 15 to the front SAM control unit via interior CAN.
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
High beam actuation is requested by pushing the combination switch (S4) forward.
The steering column tube module control unit (N80) reads in the switch position of the combination switch directly and sends this via chassis CAN 1 (CAN E1) to the front SAM control unit.
The front SAM control unit receives the switch position of the combination switch, uses it to generate the "High beams ON" request, and sends it over chassis CAN 2 to the left headlamp control unit and to the right headlamp control unit.
The left headlamp control unit actuates the left light distribution actuator motor (E1m3) directly and the left low beams (long range) and the high beam in the left front lamp unit through the left headlamp LIN and the left front actuation module, LED exterior lights.
The right headlamp control unit actuates the right light distribution actuator motor (E2m3) directly and the right low beams (long range) and the high beam in the right front lamp unit through the right headlamp LIN and the right front actuation module, LED exterior lights.
The front SAM control unit also sends the "High beams ON" request over the interior CAN to the instrument cluster.
The instrument cluster 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".
Additional function requirements for daytime running lights actuation
- "Daytime running lights" function activated in "Settings", "Light" menu in instrument cluster
- "Engine running" or "Drive train ready" signal set or vehicle speed v > 3 km/h
- Exterior lights switch in "A" position
Function sequence for daytime running lights actuation
The instrument cluster sends the request "Daytime running lights On" as a function of the country coding or manually in the "Settings" menu, "Light" activated over the interior CAN to the front SAM control unit. 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 the "Drive train operational" signal via chassis CAN 1 to the front SAM control unit.
The instrument cluster sends the vehicle speed to the front SAM control unit over the interior CAN.
The front SAM control unit reads in all the information, evaluates it and sends the "Daytime running lamps ON" request over chassis CAN 2 to the left headlamp control unit and to the right headlamp control unit.
The left headlamp control unit actuates the left position light, daytime running light and turn signal light (E1e25) and the left front position light (E1e31).
The right headlamp control unit actuates the right position light, daytime running light and turn signal light (E2e25) and the right front position light (E2e31).
In darkness the front SAM control unit also actuates the low beams. The ambient brightness is recorded by the light sensor (B38/1) (except 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 rear-view 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.
On vehicles with code 460 (Canada version), the daytime running lights actuation is switched off after expiration of a period of t = 3 min when the vehicle is standing still. If the vehicle is moved again, the front SAM control unit automatically activates daytime running lights actuation.
The daytime running lights have a higher priority than 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.
With daytime running lights the high beams are only permissible, if the driving lights are switched on manually using the exterior lights switch.
Additional function requirements for auto on/off driving lights
- "Engine running" or "Drive train ready" signal set or vehicle speed v > 3 km/h
- Exterior lights switch in "A" position
- Light sensor or rain/light sensor signals "Darkness recognized"
Function sequence for auto on/off driving lights
The auto on/off driving lights are purely a comfort function and do not relieve the driver of the need to follow the operating instructions as prescribed by the road traffic regulations.
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal via chassis CAN 1 to the front SAM control unit.
The instrument cluster sends the vehicle speed to the front SAM control unit 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 rear-view mirror LIN.
In the auto on/off driving lights, the low beams are automatically switched on or off. This takes place dependent on the ambient brightness or dependent on the windshield wiper system activities:
- Function sequence for auto on/off driving lights via light sensor or rain/light sensor
- Function sequence for auto on/off driving lights over wiper activities
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 rain/light sensor via wiper/inside rear-view 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 the windshield wiper system and evaluates the data of the rain/light sensor or the wipe request via the combination switch for this purpose.
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.
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 the auto on/off driving lights are active | ||
|---|---|---|
| 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" or "drive train operational" signal set or vehicle speed v > 3 km/h | On | On (high beams permissible) |
| End of trip | Standing lamp | Low beam |
| "Engine running" or "drive train operational" signal set or vehicle speed 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 (HRA [LWR])
- "Engine running" or "drive train operational" signal on
- Driving lights On (low beam/high beam)
Function sequence for automatic headlamp range adjustment (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 [ME] control unit sends the "Engine running" or "Drivetrain operational" signal over chassis CAN 1, front SAM control unit and chassis CAN 2 to the left headlamp control unit and the right 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 left 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 sent over the chassis CAN 1, front SAM control unit and the chassis CAN 2 to the left headlamp control unit and to the right headlamp control unit:
- Left rear level sensor
- Left front level sensor
- Right front level sensor (B22/9)
- Right rear level sensor (B22/10)
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 headlamp range adjustment is reduced sharply. The "dynamic mode" is activated depending on the speed change and additional signals from the brake and accelerator pedal positions.
When the vehicle is standing automatic headlamp range adjustment is accomplished in the "dynamic mode".
The wheel speeds, as indicators of vehicle speed, are sent by the Electronic Stability Program control unit (N30/4) over the chassis CAN 1, front SAM control unit and the chassis CAN 2 to the left headlamp control unit and to the right headlamp control unit.
Both headlamp control units receive this information and communicate with each other via chassis CAN 2.
The headlamp control units operate in a in master-slave combination, whereby the left headlamp control unit acts as the master and synchronizes the right headlamp control unit.
The left headlamp control unit actuates the left headlamp range adjustment actuator motor (E1m1).
The right headlamp control unit actuates the right headlamp range adjustment actuator motor (E2m1).
| Electrical function schematic for driving lights actuation | PE82.10-P-2059-97TAD | ||
| Overview of exterior lights system components | GF82.10-P-9998RDM |