Headlamp: Service Precautions

Headlight beam adjustment (HBA), Xenon

Introduction

General Instructions/Safety Instructions

WARNING:
- Danger of injury from high voltage.
- The light should always be switched off when removing and installing the headlights.
- The gas discharge lamp should only be operated when installed in the headlight.
- Only carry out repairs to the headlight or the wiring when the part is removed and disconnected from the power supply.
- Danger of damage due to improper handling of batteries and control module plug connections.
- Never disconnect battery with engine running.
- Never start engine if battery terminal clamps are not connected securely.
- Never pull off or push on plug connections for the control modules or other electronic components when the ignition is switched on.
- Always disconnect the negative terminal of the battery and pull off all plug connections to the vehicle electrical system control module when carrying out welding work on the vehicle.
- Coding: Make sure that the headlight system is coded correctly in the vehicle electrical system control module (always code Xenon headlights as well).
- Incorrect coding in the vehicle electrical system control module can damage the HBA Xenon control module.


NOTE:
- Communication with the HPA control module can only be established once ignition and dipped beam headlight are switched on.
- Each headlight, left and right, has its own HPA (Xenon) control module. These can be read out and coded separately.
- Following replacement of the HPA control module(s), always per form a drive link test on the HPA servomotor to check that the correct headlight is reacting (correct side)
- Before troubleshooting, always read out the fault memory of the other HPA (Xenon) control module, left or right, in order to deter mine whether faults are related.
- Both control modules also contain the switching device for the gas discharge lamp. The power supply and the switching function come from the vehicle electrical system control module.
- The fault memory of the vehicle electrical system control module must be read out before troubleshooting.
- if it is not possible to communicate with the HPA control modules in the headlight, this may be caused by incorrect coding, e.g. both headlights are coded on one side. Remedy: Remove one headlight and restart connection setup using the Tester Code control module correctly.
- In vehicles with level control (air springs), the signal for the vehicle position is received via the level control system control module. This has four angle sensors for compression.
- In vehicles without level control (steel springs), two angle sensors - front left and rear left - are installed for compression detection.