Product: Headlight Driver / Ballast Control Module (OEM A2129008324) Key benefits Improves safety: Automatically reduces headlight beam height on narrow roads to avoid blinding pedestrians and oncoming vehicles. Adds convenience: Automatically switches headlights on when entering low-light environments so you do not need to operate lights manually. OEM compatibility: Matches original equipment part numbers for accurate fit and function with specified Mercedes-Benz models. What it does Electronic driver/ballast control for adaptive headlight systems. Automatically adjusts light height and performs automatic on/off based on ambient light conditions to maintain correct headlight behavior. Compatibility and part numbers OEM part numbers: A2189007306, A2129005424, A2129008324, A2189000406 Listed part number: A2129008324 Vehicle fitment: Mercedes‑Benz Vito, V‑Class; Mercedes‑Benz chassis W212 and W207 Important attributes Function: Automatic beam height reduction in confined spaces; automatic headlight activation in low-light environments. Design: Compact electronic control module designed to meet OEM specifications for direct replacement into compatible headlamp systems. Performance: Restores correct automatic headlight control and beam leveling functions when installed in compatible vehicles. Typical use scenarios Driving on narrow residential streets at night where automatic beam lowering prevents glare for pedestrians and oncoming drivers. Entering tunnels, underground parking, or shaded areas where lights need to switch on without driver intervention. Replacing a failed or damaged headlight ballast/control module on a Mercedes‑Benz Vito, V‑Class or vehicles on W212/W207 platforms to restore proper headlight automation. Notes for buyers Confirm your vehicle’s OEM part number matches one of the listed numbers before purchasing to ensure compatibility. This module is intended as a replacement for the specified Mercedes‑Benz headlight control units and is designed to integrate with the vehicle’s existing headlight system.