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Q: Electrical components malfunction

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My car starts right up and runs fine but it's developed some electrical problems lately. Different electrical components have stopped working, such as turn signals, speedometer, windows, seats, radio along with the air conditioning. Only the lights are working properly. What might cause this? How can I fix it?

Your model Mercedes uses an electronic controller called SAM (signal acquisition module) to actually supply power to many electrical components. There are multiple SAMs in your vehicle and one of these is not working properly. A professional mechanic with specific Mercedes training, and diagnostic equipment (called STAR) is required to diagnose this issue.

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