Sidelights, parking lights

Sidelights and parking lights are legally prescribed functions for lighting up the parked vehicle.

In the sidelights switch position, both sides of the vehicle are lit up.
The parking light lights up only the side of the vehicle selected using the turn indicator-low beam switch (after ignition OFF).

Brief description of components

Light switch

The light switch consists of

Rotary switch for sidelights and low beam (and special equipment Automatic Light Control)
Two buttons for fog lights and rear fog light
Potentiometer for dimmer of panel illumination
Potentiometer for manual headlight vertical aim control in the case of halogen headlights

	S_SL	S_AL
Switch position Light OFF	1	1
Switch position Sidelights	0	1
Switch position Low beam	0	0
Switch position Automatic Light Control	1	0

Power supply: The switch is supplied with 5 Volts by the light module.

If the power supply is defective, the light remains ON:the light is automatically switched on if

the cables to and from the light switch have been cut or
are switched to earth
are at 12 V.
For safety reasons, the light switch can only be switched OFF if there is 5 V at both switch outputs to the light module. If a short circuit means that there is once 5 V and once 12 V, the light can not be switched OFF: low beam and Automatic Light Control remain ON.

Turn indicator-low beam switch

The steering-column lever to the left of the steering wheel switches the functions

Turn indicator (one-touch flashing or continuous flashing left or right) with terminal R On,
Parking light left or right: with terminal R OFF, overpress the switch beyond the engaging point, as for continuous flashing.
High beam and headlight flasher.

The steering-column lever no longer engages in the switch positions. The functions are operated by

Touching the switch to move it forwards or backwards: high beam and low beam
Touching the switch to move it to the right or left: one-touch indicating
Overpressing the engaging point: continuous flashing

If the driver operates the steering-column lever

a message is transmitted to the light module. Signal path: SZL (steering column switch centre) -> data bus BYTEFLIGHT -> SIM (Safety and Information Module) -> data bus BYTEFLIGHT -> ZGM (Central Gateway Module) -> data bus K-CAN SYSTEM -> LM (Light Module).
At the same time, the light module evaluates a direct signal from the steering-column lever. This signal is transmitted across a separate cable, making it independent of the K-CAN SYSTEM data bus.

Function limitation in the case of failure of the data buses:

High beam and headlight flasher only run if the steering-column lever is held.
The indicator light only runs if the steering-column lever is held. no continuous flashing, no automatic reset
No hazard-warning lights in the event of a crash and when arming the anti-theft alarm.

Light module

Tlight module controls and monitors the vehicle lights. Information is received and sent via the data bus K-CAN SYSTEM.

In the case of the special equipment xenon headlights, the defects of the xenon headlights are evaluated in the light module.

Emergency operation properties of the light module: The light module is supplied with terminal 30 twice.

If a terminal 30 fails, the following are activated:

Front lighting: low beam and parking light (each on one side).
Rear lighting: On one side, the outer sidelights/brake lights are activated. On the other side, the inner taillights are activated. The vehicle thus still has lights on both sides. Confusion with a one-track vehicle (motorcycle) is excluded.
Brake light: One side of the brake lights is activated with normal power (ECE coding). This leads to ”one-track” braking, as if for example one brake light had failed.

In the case of a failure of the processor, emergency operating mode is activated. Emergency operating mode involves hardware that is completely independent of the light module. Emergency operation properties with failure of the processor:

Vehicle lighting: At terminal 15 On, the following are switched on: Front low beam and outer rear sidelights / brake lights left and right. The outer sidelights / brake lights left and right are not, as would be normal, dimmed to 10% of their brightness, but operated with full power. This ensures the function of the vehicle lighting irrespective of the position of the light switch.
Brake light: With terminal 15 On, the left and right brake lights are switched on when the brake-light switch is operated (via a hard-wired, direct line from the brake-light switch to the lamp drivers).

Function defects with failure of the processor:

No turn indicators and hazard warning lights, no high beam, no headlight flasher, no fog lights, no rear fog light, no third brake light
No communication across the K-CAN SYSTEM.
No communication with the trailer module

Sidelights, front

The front sidelights are filament bulbs. The lamps are monitored by the light module.

Inner taillights, left and right

The inner taillights left and right are light emitting diodes (LEDs). The light emitting diodes are activated with 10% of their power. The light emitting diodes are not monitored by the light module.

Sidelights / outer brake lights left and right

The sidelights / outer brake lights left and right are light emitting diodes (LEDs). The LEDs are not monitored by the light module.

The sidelights / outer brake lights left and right also serve as brake lights (depending on coding or country variant):

Function of taillight: the light emitting diodes are activated with 10% of their power.
Function of brake light: in the case of strong braking, the light emitting diodes are activated at full power (depending on coding and/or country variant).

Licence plate light, left and right

The licence plate lights are filament bulbs. The lamps are monitored by the light module.

Country-specific version

USA

In the USA, additional sidemarkers are fitted:

Front sidemarkers are lamps. The lamps are monitored by the light module (on output for both lamps).
Rear sidemarkers are light emitting diodes (LEDs). The LEDs are not monitored by the light module.