Mercedes Active Headlamps Light System Inoperative
When you start up a Mercedes-Benz and turn on the lights you may get an error message stating that Active Headlamps Inoperative. The error message may vary depending on the model.
Common error messages are:
Active headlamps inoperative
Intel. Light system inoperative
When these errors are displayed on the instrument cluster, the owner may notice that the headlights may appear to work properly.
What is Mercedes 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 comes with Lightning Package and the car owner will have to pay extra.
Mercedes vehicles that have active headlamps have the following code in the Datacard.
Includes 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 rotated.
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.
This problem is not related to auto on light feature which is often caused by a defective rain/light sensor mounted near the top of the windshield.
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/rear or side of the dashboard.
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. Make sure the wire harness is pressed firmly into the headlight assembly. It is possible that the wires inside the headlight may also be damaged.
There is a high chance that the motor that moves the low beam reflector has failed or it 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 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 active headlight system.