This control unit is responsible for managing and controlling various vehicle lighting functions, particularly the headlights (low beam, high beam, LED daytime running lights, etc.). It interacts with other electronic systems in the car to ensure the lights function correctly based on driving conditions and the settings selected by the driver.

In general, electronic control modules in modern cars serve to:

• Improve driveability and efficiency: They allow for more precise and responsive control of the vehicle's various functions.

• Reduce emissions: They help optimize the operation of systems for greater efficiency.

• Increase reliability: They monitor and manage components to prevent malfunctions.

• Provide self-diagnosis: Detect and report any problems via error codes.

Why change the 31395946 control unit?

Replacing this control unit is necessary in the event of malfunctions or damage that compromise the proper functioning of the headlights. The main reasons why a control unit of this type might fail include:

1. Surge voltages in the on-board network: Voltage fluctuations can damage internal electronic components.

2. Overheating and temperature changes: Extreme conditions can compromise the integrity of the control unit.

3. Corrosion/Moisture: Water or moisture ingress can oxidize internal components and circuits.

4. Depressurization: Sealing problems can expose components to external elements.

5. Mechanical Damage: Shocks or vibrations can cause physical damage to the control unit.

6. Delamination of the printed circuit board, oxides on the contact tracks, etc.: Internal defects or aging of the materials.

Signs that indicate a fault in the light control unit (31395946):

• Instrument cluster error icon: A warning light that indicates a problem with the headlights or lighting system.

• Error messages on the vehicle display: The system may display specific messages relating to headlight malfunctions.

• Headlights that don't work properly: For example, they don't turn on, they flicker, they have reduced brightness, or automatic functions don't work.

• Actuator problems (if equipped): If the module also controls headlight aiming or other functions, these may not work.

• The module is not detected by the diagnostic scanner: If a mechanic connects a diagnostic tool and it cannot communicate with the ECU, it is a strong indicator of a fault.

Part Number:

• 31395946

Suitable for:

• XC90
• S90
• V90