Function of Xenon headlamp - ra82001404630x(4630)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

A. Location of components, B. Function Model 140

A. Location of components

Fig 1: Identifying Right And Left Headlamp Unit Components Location

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

B. Function

Xenon bulb (D2R)

The combustion chamber for the xenon bulb is filled with xenon and a mixture of metal halide salts. This mixture is ignited by high voltage. The color of the light has a character similar to daylight.

Function

When the low beam is switched on the xenon headlamp control module (E1n1, E2n1) activates the xenon headlamp ignition module (E1n2, E2n1) within a few milliseconds via the control voltage. The high voltage surge (approx. 20kV) from the ignition module strikes an arc between the electrodes in the xenon bulb. When an arc of sufficient stability is recognized, the electronic control circuitry in the control module (E1n1, E2n1) switches over to the power limiting mode. The electric power is regulated to 35 W.

A voltage transformer provides the voltage of approx. 85 V (AC) required for reliable function of the xenon bulb. Xenon bulbs require a start-up time due to the technology. After switch-on 50 % of the brightness is achieved within one to two seconds and the full brightness is reached after approx. 30 seconds.