Headlamp Switch: Description and Operation

GF82.10-P-2011LE 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)
^ Function activated via the COMAND controller unit (A40/3)
^ Engine switched off and transmitter key (A8/1) removed
^ Rain/light sensor (B38/2) signals "Darkness detected"
^ Rotary light switch (S1) in position "AUTO" (with code (494) USA version)

SWA, general
The SWA is used for leaving and finding the vehicle safely in darkness by switching on the vehicle ambient illumination.

SWA 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)
The following signals are evaluated by the front SAM control unit with fuse and relay module (N10/1) for output of the headlam switch-off delay function:
- Activated "Locator lighting" function provided by COMAND control unit to the central CAN (CAN F) and relayed by the central gateway control unit (N93) via the interior CAN (CAN B)
- The circuit 15 status provided on the interior CAN by the electronic ignition switch control unit (N73)
- The status of circuit 61 is provided by the CDI control unit (N3/9) (on diesel engine) or by the motor electronics control unit (N3/10) (on gasoline engine) on the chassis CAN (CAN E).
- Status of rain/light sensor provided on the interior CAN by the overhead control panel control unit (N70)
- Status of rotary light switch, sent by upper control panel control unit (N72/1) to interior CAN (with code (494) USA version)

After switching off the engine, the vehicle ambient illumination is switched on for an adjustable time interval of t = maximum 60 s. When a vehicle door or the trunk lid is opened, the time interval starts again. When all vehicle doors are closed again, the function is initiated again for the configured time interval.

The time interval can be adjusted in 15 s increments from t = 0 to 60 s.

The status of the corresponding vehicle door is provided to the interior CAN:
- Model 216:
- Driver door by left door control unit (N69/1)
- Passenger door by right door control unit (N69/2)

- Model 221:
- Driver door by left front door control unit (N69/1)
- Passenger door by right front door control unit (N69/2)
- Left rear door by left rear door control unit (N69/3)
- Right rear door by right rear door control unit (N69/4)

The rear SAM control unit with fuse and relay module (N10/2) sends the status of the trunk lid to the interior CAN.

The front SAM control unit receives all the relevant information, evaluates it and transmits a corresponding signal via the interior CAN to the following control units.
- Left door control unit (model 216)
- Right door control unit (model 216)
- Left front door control unit (model 221)
- Right front door control unit (model 221)
- Rear SAM control unit
- Trailer recognition control unit (N28/1) (for code (550) Trailer hitch)

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

On model 221 as of 1.6.09 with code (615) Bi-xenon headlamp unit with integrated curve illumination or code (616) Xenon headlamp unit with asymmetrical integrated curve illumination or code (621) Intelligent Light System (left-hand traffic) or code (622) Intelligent Light System (right-hand traffic), for the output of the parking light and standing light functions conventional LEDs are used. For this purpose the left standing and parking light voltage converter is located at the bottom of the left front lamp unit (E1) E1n5 and the right standing and parking light voltage converter at the bottom of the right front lamp unit (E2). E2n5 They are supplied with voltage by the front SAM control unit.

- Model 216, model 221 up to 31.5.09, model 221 as of 1.6.09 without code (236) Daytime running lights in LED version:
- Left front fog lamp (E5/1)
- Right front fog lamp (E5/2)

- Vehicles with code (494) USA version:
- Left front side-marker lamp (United States Of America E6/1)
- Right front side-marker lamp (United States Of America E6/2)

The left door control unit receives the request and actuates the left outside mirror ambient lamp (M21/1e1).

The right door control unit receives the request and actuates the right outside mirror ambient lamp (M21/2e1).

The rear SAM control unit receives the request and actuates the following components in the vehicle's ambient illumination:
- Left brake light, taillight and parking light (E3e9)
- Right brake light, taillight and parking light (E4e9)
- Left license plate lamp (E19/1) and
- Right license plate lamp (E19/2)
- Vehicles with code (494) USA version:
- Left rear side marker lamp (United States Of America E3e6)
- Right rear side marker lamp (United States Of America E4e6)

The trailer recognition control unit receives the request and actuates the corresponding components for the lighting system on the trailer through the trailer hitch socket, 13-pin (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 by means of the transmitter key. The EIS control unit transmits the request "Unlock vehicle" via the interior CAN to the front SAM control unit.

The front SAM control unit issues the request "Switch on vehicle ambient illumination" via the interior CAN to the corresponding control units. The components are actuated as described for the headlamp switch-off delay (SWA) function.
The AFB function is terminated by opening a vehicle front door, by inserting the transmitter key into the EIS [EZS] control unit or by triggering an ATA [EDW] alarm.

The headlamp switch-off delay and locator lighting functions run in parallel if necessary. An active headlamp switch-off delay (SWA) function is not terminated by a requested AFB function and vice versa.