Headlamp Switch: Description and Operation

GF82.10-P-2011CA Headlight Switch Off Delay Function

Function requirements for headlamp switch-off delay (SWA), general

^ No overvoltage or undervoltage (operating voltage range U ≥7 ≤17.5 V)
^ "Ambient illumination:" function activated in "Settings", "Light" menu in instrument cluster (A1)
^ Rain/light sensor (B38/2) signals "Darkness detected"
^ Exterior lights switch (S1) in "AUTO" position with code (460) Canada version or code (494) USA version)

SWA, general
The headlamp switch-off delay (SWA) function is used for leaving and finding the vehicle safely in darkness by switching on the vehicle ambient illumination.

The headlamp switch-off delay (SWA) function consists of the following subfunctions:
^ Function sequence for headlamp switch-off delay (SWA)
^ Function sequence for locator lighting (AFB)

Function sequence for headlamp switch-off delay (SWA)
After switching off the engine by turning the transmitter key (A8/1) in the electronic ignition lock control unit (N73) or by pressing the KEYLESS-GO start/stop button (S2/3) (with code (889) Keyless Go) (change of status of circuit 15 On to circuit 15R On), the headlamp switch-off delay function is requested.

The following information is evaluated by the front SAM control unit with fuse and relay module (N10/1) for output of the headlamp switch-off delay function:
- Activated headlamp switch-off delay function provided by the instrument cluster on the interior CAN (CAN B)
- The circuit status of circuit 15 is provided by the electronic ignition lock control unit on the interior CAN
- Status of rain/light sensor read in via wiper/inside rearview mirror LIN (LIN 2)
- Exterior lights switch status read in via instrument panel LIN (LIN 1) (model 207.3 up to 31.5.10) or directly (model 207.3 as of 1.6.10, model 207.4)

After switching off the engine, the vehicle's ambient illumination is switched on for a fixed time interval of t = 60 s. The time interval starts again by opening a vehicle door. The trunk lid is assessed as a vehicle door. Once all vehicle doors are closed again, this time interval is limited to t = 15 s.

The status of the doors is sent by the left front door control unit (N69/1) and the right front door control unit (N69/2), the status of the trunk lid by the rear SAM control unit with fuse and relay module (N10/2) via interior CAN to the front SAM control unit, which evaluates all relevant information and sends a corresponding signal via interior CAN to the following control units:
- Rear SAM control unit
- Trailer recognition control unit (N28/1) (with code (550) Trailer hitch)

The following components of the vehicle ambient illumination are actuated by the front SAM control unit:
- Left front standing light and parking light (E1e3)
- Right front standing light and parking light (E2e3)

- Additionally in vehicles with code (615) Bi-xenon headlamp unit with integrated curve illumination or code (616) Bi-xenon headlamp unit with integrated asymmetrical curve illumination or code (621) Intelligent Light System (left-hand traffic) or code (622) Intelligent Light System (right-hand traffic):
- Left xenon bulb with integrated ignition module (E1e10)
- Right xenon bulb with integrated ignition module (E2e10)

- Additionally, in vehicles with code (498) Japan version or without code (615) Bi-xenon headlamp unit with integrated curve illumination and without code (616) Bi-xenon headlamp unit with integrated asymmetrical curve illumination and without code (621) Intelligent Light System (left-hand traffic) and without code (622) Intelligent Light System (right-hand traffic):
- Left fog lamp (E5/1)
- Right fog lamp (E5/2)

- Additional with vehicles with code (460) Canada version or code (494) USA version
- Left front side-marker lamp (E6/1)
- Right front side-marker lamp (E6/2)

The following components of the vehicle's ambient illumination are actuated by the rear SAM control unit:
- Outer left brake light and taillight (E3e11)
- Outer left background light (E3e15)
- Inner left brake light and taillight (E3/1e4)
- Inner left background light (E3/1e6)
- Outer right brake light and taillight (E4e11)
- Outer right background light (E4e15)
- Inner right brake light and taillight (E4/1e4)
- Inner right background light (E4/1e6)
- Left license plate lamp (E19/1)
- Right license plate lamp (E19/2)

The trailer recognition control unit actuates the taillights and parking lights of the trailer via the trailer socket (X58).

By briefly switching on circuit 15 after switching off the engine, it is possible to discretely leave the vehicle without activating the headlamp switch-off delay.

The active headlamp switch-off delay is terminated immediately by switching on circuit 15 or by triggering an anti-theft alarm system (ATA [EDW]) alarm (with code (551) Anti-theft alarm system (ATA [EDW])).

Function sequence for AFB
The vehicle ambient illumination is switched on for a period of approx. t = 40 s when the vehicle is unlocked using the unlock button on the transmitter key.
The electronic ignition lock control unit transmits the request Unlock vehicle" via the interior CAN to the front SAM control unit. The front SAM control unit evaluates it and transmits the request Rear lamps On" via interior CAN to the rear SAM control unit and to the trailer recognition control unit.
The components of the vehicle ambient illumination are actuated as described for the headlamp switch-off delay function.
The locator lighting function is aborted when a door is opened, the transmitter key is inserted into the electronic ignition lock control unit, or when an anti-theft alarm system alarm has been triggered.

The headlamp switch-off delay and locator lighting functions run in parallel if necessary. However, an active headlamp switch-off delay function is not terminated by a requested locator lighting function and vice versa.