Headlamp: Application and ID

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.

WARNING:
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.

WARNING:
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 HBA control module can only be established once ignition and dipped beam headlight are switched on.
- Each headlight, left and right, has its own HBA (Xenon) control module. These can be read out and coded separately.
- Following replacement of the HBA control module(s), always perform a drive link test on the HBA servomotor to check that the correct headlight is reacting (correct side)
- Before troubleshooting, always read out the fault memory of the other HBA (Xenon) control module, left or right, in order to determine 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 HBA 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.

Troubleshooting procedure
Specific troubleshooting can only be performed in accordance with instructions (given under Diagnosis/troubleshooting for each fault code) if the entry has the status 'present' in the fault memory.

If the fault is currently 'not present', please check the following:
- Diagnostic conditions are met.
- All plug connections and ground points of the affected current path are OK.
- Set all wiring harnesses of the affected current path to a state that corresponds to driving by pulling and shaking them.

Diagnostic conditions

NOTE:
Important: Always connect a suitable battery charging device to the vehicle electrical system battery before starting diagnosis. All unnecessary loads must also be switched off.

NOTE:
The fault can only be identified if the requirements listed under 'Diagnostic conditions' are met. For this reason, the specified procedure must be observed after a fault is repaired:
1. Erase fault memory
2. Satisfy the requirements listed under 'Diagnostic conditions'.
3. Read out fault memory again.

Possible causes of fault

NOTE: The 'possible causes of fault' that are responsible for the fault are listed here. Please note that in certain circumstances further faults can be stored in the fault memory after troubleshooting (e.g. if plugs are disconnected). After carrying out repairs, read out the fault memory of all control modules and erase any faults.

Diagnosis/troubleshooting

Fault status
The following status types are possible:
- present
- not present