How to protect the modules in 2019 Mercedes models while tinting.
Method 1: On both front doors of the CLA250 and C300 are holes in the paneling that lead to the modules. Remove the door panels and pull the small tabs off. Then stuff these holes with cloth, paper towels, or anything else laying around that can prevent the entry of moisture. For extra precaution, you can go inside the panel and find the module itself, usually a white rectangular box with wires connected to it, and cover that. While tinting, use a soak rope, and/or cover the entire door panel with tinting covers.