They auto shutoff once cars started, even in darkness;No handle to alter auto-lights in car;Tried unhooking battery to reset electronics, no luck.06 Volkswagen Passat 2.0t
The Passats have the light management system that can be set using the VCDS terminal and interface cable connected to the car. It also takes a trained mechanic to use it properly. When hooked, it will show any problems - that is the starting point. It is also important to know WHEN this weird behavior started - did it come out of the blue or was it event-related, such as installing HIDs or some other aftermarket item, changing bulbs with LED ones etc. This will help understand the origin of the problem and roughly show the way to the proper solution. If there are no fault codes, the lights section should be checked and set properly. The auto lights sense the outdoor light levels and operate lights (nighttime, tunnels, dark daytime), plus manage the leaving/coming home function that switches low beams with unlocking and leaves them on for about 30...45 sec after locking.
ZZ is right. I would add that the windshield may have been replaced with the wrong windshield, blocking the rain/light sensor on the rear view mirror. Without a properly operating light sensor, Auto Headlight operations are not going to happen. If the headlights won't come on with the Headlight switch in the On position, I would look at the switch, the car battery, or the charging system.
