At startup, Mercedes-Benz vehicles may display an error message stating that Active Headlamps are Inoperative.
Example of active headlamps inoperative warning.
Common error messages that come up on instrument cluster:
- Active headlamps inoperative
- Intell. Light system inoperative
- Active light system inoperative
- Intelligent Light System Inoperative
The headlights will turn on, but they are not working properly.
This warning is common on Mercedes-Benz vehicles that are equipped with Lightning Packages such as bi-xenon high-intensity discharge (HID) active headlights with headlight washers and corner-illuminating foglights. The active headlights progressively pivot in the direction of the driver's intended path, derived by how far the steering wheel has been turned left or right.
Corner-illuminating foglights throw a fixed beam of light in the direction the steering wheel is being rotated or whenever a turn signal is activated. These foglights function in that manner when the vehicle is traveling at speeds below 25 mph.
The most common problems that trigger Active Headlamps Light System Inoperative.
Faulty Reflector Motor
There is a high chance that the motor that moves the low beam reflector has failed or is not getting power.
Inside the headlight, you will notice one small motor and gear that connect to the low beam /projector lamp. When the motor is turned on, it moves the low beam, which is what is called the Active Light System.
The motor can fail due to high heat, water intrusion and trigger the active headlamp inoperative message. A short circuit can also cause the Active Light System to stop working.
Check that 12-volt power is going to the headlight to power the motor. Check the motor for continuity to verify the motor isn't defective.
If the motor has failed, it can be difficult to replace. It will require that the headlight assembly is removed. Next, you will need to open the headlight to access the motor.
A temporary solution would be to manually adjust the low beam reflector/project to the proper position. This will make the low beams function as they do on cars without an active headlight system.
Check fuses for the active headlight system. The fuses for the active headlight system will most likely be in the fuse box located in the trunk or side of the dashboard, depending on the model.
Bad Wires Harness
Check that the low beams are working. If they aren't, there may be a problem with the wire harness that goes to the headlight or the wires inside the headlights.
Make sure the wire harness is pressed firmly into the headlight assembly.
The wires inside the headlight may also be damaged or shorted.
A faulty headlight module can also be the reason why you may get active headlamps to stop working. The hardware inside the module can fail most commonly due to corrosion or a software glitch can prevent it from working properly.
For further troubleshooting read the fault codes with a Mercedes-Benz scanner.
How do I know if my Mercedes has Active Headlamps?
The active headlamp system adjusts the low beam reflector for better visibility and light projection based on vehicle speed and steering wheel position. Not all Mercedes-Benz vehicles have this feature. It is part of the Lightning Package, which for most models, is an add-on option.
Mercedes vehicles that have active headlamps have the following code in the Datacard.
- 615 - BI-XENON HEADLIGHT W.ACTVIE CURVE LIGHT RIGHT-DRIVE