Headlamp Igniter Module: Service and Repair
Removing And Installing Control Module For Gas Discharge Lamp
WARNING: Risk of short circuit: Before removing the headlight, take out the ignition key and switch the light switch off.
NOTE:
- The control unit is located underneath the Bi-Xenon headlights.
- The control unit controls the motors for the headlight beam adjustment (HBA) of Bi-Xenon headlights.
Removing Control Unit For Gas Discharge Lamp
1. Switch off light. Remove main headlight.
2. Open the two locking bars "1" and remove the cover "2".
3. Turn the headlight over and set down on a suitable base.
4. Remove all six fastening screws "3" and pivot up the control unit.
5. First actuate the lock on the connector "5" and remove the connector. Open the clip on the connector "4" and unplug the connector.
WARNING: Risk of damage to the control unit for the gas discharge lamp: It is essential to pull the connectors "4" and "5" straight out.
6. Remove the seal "A" from the headlight.
Installing Control Unit For Gas Discharge Lamp
WARNING: Risk of damage to the control unit for the gas discharge lamp: It is essential to insert the connectors "4" and "5" straight in.
NOTE: Ensure that the seal "A" is properly positioned on the control unit.
1. Insert the connector "4" and secure with the locking bar. Press in the connector "5" until it locks in place.
2. Position the control unit and secure it with the six fastening screws, starting in the middle. Tightening torque 3 Nm (2 ftlb.).
3. Place the cover "2" in position, press on and then close the locking bar "1".
4. Install main headlight and perform a function test.
Coding And Calibration
CAUTION:
- Coding: make sure that the headlight system is coded correctly in the vehicle electrical system control unit (always code Bi-Xenon headlights as well).
- Incorrect coding in the vehicle electrical system control unit can damage the control unit for the HBA Bi-Xenon gas discharge lamp.
NOTE:
- Communication with the HBA gas discharge lamp control unit can only be established once ignition and dipped beam are switched on.
- Each Bi-Xenon headlight, left and right, has its own HBA (Xenon) gas discharge lamp control unit. These can be read out and coded separately.
- Following replacement of the HBA control unit(s) of the gas discharge lamp, 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 control unit for the gas discharge lamp, left or right, in order to determine whether faults are related.
- The power supply and the shift 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 unit for the gas discharge lamp 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 unit. 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.
Extracting and changing the coding
Under menu item:
- Special functions
- HBA left or right
Coding can be read out indicating which equipment features are activated and which are not.
The following equipment features can be set:
- Control unit, right
- Control unit, left
- Right control unit in connection with level control system
- Left control unit in connection with level control system
- Read out the fault memory again and erase as necessary
- If a fault is present, then Refer to Technical diagnosis.
CAUTION:
- 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 unit can damage the control unit for the HBA gas discharge lamp.
Calibration
NOTE:
- Calibration must be performed in the control unit for the level control system in all vehicles with level control system chassis
- The level control system control unit provides the parameters for the gas discharge lamp to the control unit for headlight beam adjustment.
The gas discharge lamp control unit is adapted to suit current conditions relating to position in the vehicle under the menu item "Calibration". The existing vehicle position is stored as zero position during calibration.
Following calibration, the headlight setting must be checked and corrected if necessary.
Calibration must be performed if changes have been made that can change the position of the angle sensors for the level control system control unit chassis:
- Headlights, complete
- Control unit, gas discharge lamp
- Angle sensors, level control system (front and rear compression)
- Running gear components
- Damage caused by accidents
NOTE:
- When the coding has been changed in the menu item Change coding, the menu in the tester must be exited and the menu must be called up again. Light off or switch it on again.
- If the coding does not match the vehicle equipment, faults will be displayed that are not really present.
- Read out the fault memory again and erase as necessary
- If a fault is present, then Refer to Technical diagnosis.