2013 Mercedes-Benz SL-Class Electrical System Problems

Had some issues with turn signals and a check engine light. My car is a 2013 SL63 AMG with 22700 miles. It sits in garage 95 percent of the time under cover. Took car to dealer and they replaced both batteries it fixed al of the lights except my turn signal. I asked the dealer why didn't you check the turn signal I got no response. I had to drive to Louisville the next day and on the way home I noticed my headlights were out and had to drive 75 miles with only fog lights. I took it to another mechanic who took the bumper off and was shocked and how much water was in my headlights and in my electrical components. He said I'm lucky the car didn't shut down or catch fire and sent me pictures of water and a brown sludge he said was some kind of manufacture fix to absorb water in the lens. He said he has never seen anything this bad on such a nice low mile car. I told him I have complained to dealer many times over the years about fog and water in my headlights and every time they would say its normal it will evaporate out of the lenses. But it also left spots and dirt inside the lenses you cant get to clean. It was so frustrating they would do NOTHING about it when I was under warranty. I researched online and found many other similar complaints with jerry rig fixes the dealers would try as they never want to replace the defective headlamp as the cost to much. This is a manufacture issue and they know about it and they just push it under the rug because they don't want to pay for the recall to fix all these cars. Its sad where is the quality anymore and the safety for consumers. I read a blog where the water shorted out his computer and he lost all controls of car steering and everything. Sad that they take profit of safety for it customers.