Automatic Low Beam Switch-on
Component Identification:
Function sequence
Function prerequisites:
- Ignition: ON
- Light switch in position "0"
- "Automatic low beam switch-on" activated
1 The overhead control panel control module (N70) evaluates the following input variables:
- signal from automatic light switch daylight sensor (B32/1)
- rain sensor signal (B38) or position of wiper switch
- vehicle speed signal
2 The overhead control panel control module (N70) transfers a corresponding signal (2) to the left front SAM control module (N10/6) via the data bus.
NOTE: The headlamps are switched on upon recognition of:
- Darkness/dusk
- Driving through a tunnel
- Rain or snow (not fog)
- Failure of a sensor
3 The instrument cluster (A1) transfers a signal (1) into the left front SAM control module (N10/6) via the data bus indicating that the "automatic headlamp/tunnel circuit feature" is activated.
4 The left front SAM control module (N10/6) transfers signals (3, 4) to the right front SAM control module (N10/7), rear SAM control module (N10/8) and trailer recognition control module (N28/1) via the data bus.
6 The left front SAM control module (N10/6), right front SAM control module (N1O/7) and rear SAM control module (N10/8) switch on the following lights:
- Left low beam (E1e2)
- Right low beam (E2e2)
- Left standing and parking lamp (E1e3)
- Right standing and parking lamp (E2e3)
- Left tail and parking lamp (E3e2)
- Right tail and parking lamp (E4e2)
- Left license plate lamp (E19/1)
- Right license plate lamp (E19/2)
7 The trailer recognition control module (N28/1) actuates the trailer hitch socket (13-pin, X58)
NOTE: Extraneous light, e.g. from other traffic, street lights, light reflections and advertising do not cause the head lamps to switch off.
The automatic headlamp/tunnel switch-on feature is a pure convenience feature and does not relieve the driver of the responsibility of observing the traffic laws. The rotary light switch always has the highest priority for switching on the headlamps. The high beams can be switched on when the automatic headlamp/ tunnel switch-on feature is active.
The following lamps are switched on automatically in the event of simple malfunctions in the electronic circuitry regardless of the adjustable "automatic low beam switch-on feature":
- In the event of a failure of the data bus (CAN) or the left front SAM control module (N10/6):
- Right standing and parking lamp (E2e3)
- Left low beam headlamp (E1e2)
- Left and right tail and parking lamps (E3e2, E4e2)
- Left and right license plate lamps (E19/1, E19/2)
- In the event of a failure in the rear SAM control module (N10/8):
Prerequisite: Ignition: ON
- Left and right tail and parking lamps (E3e2, E4e2)
- Left and right license plate lamps (E19/1, E19/2)
- In the event of a failure in the trailer recognition control module (N28/1):
Prerequisite: Ignition: ON
- Trailer tail lamps