The light module controls and monitors
Diagnosis as well as communication with other control units takes place via the I-bus.
In the event of failure of the control unit or one of its peripheral elements, an emergency operation facility enables the functions parking/tail/low beam/break light as well as turn signal indicators.All other functions as well as communication via the I-bus (diagnosis) are then not possible.
If a trailer coupling is installed in the vehicle, the lamp circuits of the vehicle must be separated by means of a trailer module from those of the trailer.The light module is connected to the trailer module by means of a data link.
With the exception of the brake light switch, all switches monitored by the light module are designed such that they switch with respect to ground.
Following switches are monitored by the light module:
The light module receives further information via the I-bus.
When the light switch is in rest position, all contacts are closed (R < 1 Ohm), the corresponding contact is opened in low beam or high beam setting (R > 1 MOhm).
Illumination of the light switch is controlled separately by the light module.It lights with full brightness when the light switch is in "OFF" position and the coded terminal condition is fulfilled. It is dimmed in the same way as the instrument lights and search light when they are switched on.
The brake light switch is permanently monitored by the light module when terminal R is activated.
It is designed as a Hall generator and features 3 lines:
A test switch is not necessary.
The indicator lamp for the hazard warning function is integrated in the hazard warning button.It also serves as a locating light.If the hazard warning system is activated, the indicator lamp is switched to maximum brightness during the "ON phase" of the turn signal indicators.It is switched off in the "OFF phase" of the turn signal indicators.
The dimmed instrument, search and function lighting (terminal 58g) is activated with the light switch set to position "parking light" or "low beam".
This function is dependent on the terminal conditions.
The voltage generated at terminal 58 g is pulse width modulated and dependent on the position of the dimmer potentiometer.
The dimmer potentiometer is switched with respect to ground.
The lamps for the vehicle lighting system are monitored when both switched on and off (cold and warm monitoring).
The result is sent to the check-control module via the I-bus.
The lamps are activated by means of transistors. Since they are short-circuit protected, the lamp fuses as used previously are rendered unnecessary.
The lamps can be activated via diagnosis function.
The country-specific functions of the lamp circuits are coded in the light module.
If one of the turn signal indicator lamps - not one of the auxiliary signal lamps - is defective, the flashing frequency is doubled.
The auxiliary turn signal indicator lamps are controlled together with the front turn signal indicator lamps.
The light module controls the voltage supply for both automatic as well as for manual headlight beam throw control.
It is switched at terminal 15 or "light ON".The headlight beam throw control system starts a reference run when the supply voltage is switched on.