Hey there, I just wanted to ask for some advice. I recently picked up this 2014 E350 and everything was going great until it started getting colder and wetter outside. That's when I noticed that the driver's side headlight was filling up with moisture. And then, bam, I get this error message saying "adaptive headlight inoperative / turn signal inoperative." I'm pretty sure the moisture killed the ballast, so I bought a new one (https://www.ebay.com/itm/134312039378) and some new headlight covers (https://www.ebay.com/itm/185639057819). But the weird thing is, when I heat up the headlights in the garage, they work perfectly fine. Any idea what could be going on here? I could really use some help figuring this out.

 

well, its pretty obvious moisture is getting in. and when it dries out its working. so you need to figure out HOW its getting in and re-seal it. I doubt the power module is the problem.

 

Thanks for the reply,
This guy had same issue and changing the ballast fixed it for him.