Xenon Light, Right

Xenon Light

In the same way as the conventional headlights, the xenon light is based on a redundant design; faults or damage in the area of one headlight does not result in disturbances in the operation of the other headlight.

High beam is still produced by headlights with halogen lamps and, for reasons of improved visibility, it is switched together with low beam.

The xenon light control unit is supplied by Bosch. It is installed in the E38 and does not feature self-diagnosis capabilities.

Caution! Relevant safety and accident prevention regulations must be observed when conducting all tests and work on the Xenon light system. The Xenon light headlight system carries dangerous high voltages.

Components
The xenon light system consists of the following components: Headlight with D2 lamp (gas discharge lamp) and the electronic ballast required to operate the D2 lamp. The electrical ballast itself consists of an ignition and a control unit.

The ignition unit serves the purpose of generating the high voltage necessary for igniting the electrical arc in the lamp. An electric arc is produced between two opposing electrodes in the D2 lamp by means of pulse ignition when an ignition voltage (18 to 25 kV) is applied. During continuous operation, the power output of the D2 lamp is 35 W and max. 75 W during start-up. Compared to the halogen lamp H1, the light yield of the D2 lamp is approximately double as much while the power input is approx. 30% lower. The D2 lamp is switched off and on again if incorrect voltage is supplied.

Input voltage Remarks
7.5 V - 16.5 V Operating voltage range
9.0 V - 16.5 V Ignition
9.0 V - 16.5 V Automatic re-ignition

Temporary voltage fluctuations do not result in the light switching off. The control unit only switches off when the supply voltage is outside the specified operating voltage range for at least 0.5 seconds. Re-ignition takes place if the lamp goes out unintentionally. In order to avoid continuous re-ignition in the case of a defective lamp, the number of re-ignition attempts is limited to five.

Safety Path
In the event of glass breakage, an integrated safety path ensures persons cannot be injured if contact is made.

The safety path consists of one supply line and one return line. These two lines are routed in a fixed wiring harness from connector 2 of the control unit via the ignition stage to the headlights.

The supply and return line forms a voltage divider together with resistors in the control unit and the glass break sensor (resistor on headlight lens). The return line from the glass break sensor is routed via a reed contact which is closed when the screw cap is fitted in position.

If the screw cap is now opened, plug connector 2 on the control unit is disconnected, breaks the lens located in front of the UV light or the line for the safety path is interrupted so that the xenon light is switched off by the control unit.