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Home >> Mercedes Benz Truck >> 2012 >> R 350 4MATIC (251.157) V6-3.5L (276.958) >> Repair and Diagnosis >> Lighting and Horns >> Sensors and Switches - Lighting and Horns >> Headlamp Switch >> Description and Operation

Headlamp Switch: Description and Operation



GF82.10-P-2011GM 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 instrument cluster (A1)
^ Rain/light sensor (B38/2) signals "Darkness detected"
^ Rotary light switch (S1) in the "AUTO" position (with code (460) Canada version or with 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 and removing the transmitter key (A8/1) from the EIS [EZS] control unit (N73) the headlamp switchoff delay (SWA) function is requested.

The following information is evaluated by the front SAM control unit (N10) for output of the headlamp switch-off delay (SWA) function:
- Activated headlamp switch-off delay function provided by the instrument cluster on the interior CAN (CAN B)
- Circuit status of circuit 15 provided on the interior CAN by the electronic ignition switch control unit
- Data from the rain/light sensor provided on the interior CAN by the overhead control panel control unit (N70)
- Status of rotary light switch provided on the interior CAN by the upper control panel control unit (N72/1)

After switching off the engine, the vehicle ambient illumination is switched on for a time interval of t = 60 s. When a vehicle door or the liftgate is opened, the time interval restarts.
The rear SAM control unit (N10/8) transmits the status of the vehicle doors and the liftgate via the interior CAN to the front SAM control unit.

The front SAM control unit evaluates all of the relevant information and transmits the request to switch on the vehicle ambient illumination via the interior CAN to the following control units:
- Rear SAM control unit
- Left front door control unit (N69/1)
- Right front door control unit (N69/2)

The following components of the vehicle ambient illumination are actuated by the front SAM control unit:
- Left standing and parking lights (E1e3) (model 164)
- Right standing and parking lights (E2e3) (model 164)
- Left standing and parking lights (E6/13) (model 251)
- Right standing and parking lights (E6/14) (model 251)

- Model 164.1, model 251.0/1, model 164.8 up to 30.6.09 and as of 1.7.09 with code (498) Japan version or without code (615) Bi-xenon headlamp unit with integral curve illumination and without code (616) Bi-xenon headlamp unit with integral asymmetrical curve illumination and without code (621) Intelligent Light System (left-hand traffic) and without code (622) Intelligent Light System (right-hand traffic))
- Left front fog lamp (E5/1)
- Right front fog lamp (E5/2)

- Additional with vehicles with code (460) Canada version or code (494) USA version
- Left side marker lamp (E1e6) (model 164)
- Right side marker lamp (E2e6) (model 164)
- Left front side marker lamp (United States Of America) (E6/1) (model 251)
- Right front side marker lamp (United States Of America) (E6/2) (model 251)

The following components of the vehicle ambient illumination are actuated by the rear SAM control unit:
- Model 164.1 without code (849) Spare wheel holder/spare wheel:
- Left taillight and rear fog light (E3e2)
- Left taillight, side marker lamp, parking light (E3e8)
- Right taillight and rear fog light (E4e2)
- Right taillight, side marker lamp, parking light (E4e8)
- Left rear-end door license plate lamp (E19/3)
- Right rear-end door license plate lamp (E19/4)

- Model 164.8 without code (849) Spare wheel holder/spare wheel:
- Left brake light (E3e4)
- Left taillight, side marker lamp, parking light
- Right brake light (E4e4)
- Right taillight, side marker lamp, parking light
- Left rear-end door license plate lamp
- Right rear-end door license plate lamp

- Model 164 with code (849) Spare tire holder/spare tire:
- Left brake light and taillight (E3/5e4)
- Left taillight, side marker lamp, parking light
- Right brake light and taillight (E4/5e4)
- Right taillight, side marker lamp, parking light
- License plate lamp, left spare tire carrier (E19/5)
- License plate lamp, right spare tire carrier (E19/6)

- Model 251:
- Left brake light, taillight, parking light, and side marker lamp (E3e9)
- Right brake light, taillight, parking light and side marker lamp (E4e9)
- Left rear-end door license plate lamp
- Right rear-end door license plate lamp

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

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

The instrument cluster is notified about the active headlamp switch-off delay (SWA) function by the front SAM control unit via the interior CAN, so that the lights on reminder function is suppressed.

If standing light or low beam actuation is active in the background of the headlamp switch-off delay (SWA) function because of the position of the rotary light switch, the lights on reminder function is output via the warning buzzer (A1h1)

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

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

Function sequence for AFB
The vehicle ambient illumination is switched on for a time interval of approx.t = 40 s when the vehicle is unlocked using the transmitter key.
The request "Unlock vehicle" is transmitted to the front SAM control unit by the electronic ignition switch control unit via the interior CAN. The components are actuated as described for the headlamp switch-off delay (SWA) function. The locator lighting function is terminated by opening the driver door or by inserting the transmitter key into the electronic ignition switch control unit.

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.





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