The best way to test for the draw would be to hook your amp meter to the negative side of the battery between the terminal and the cable. If the car you are testing is the sel in your sig then the acceptable draw will be about 25 to 30 milliamps after any components that need to energize have done so. The most common component to cause problems on that car would be the automatic antenna. You also want to be sure that your trunk and glove box lights are turning off. About the only thing pulling any juice normally will be the clock in the instrument cluster.

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Mercedes Benz Master Tech - Retired