If you are looking for an inexpensive way to test the electrical circuits on your Mercedes here is a good option. This tester reads both AC and DC voltage, DC current, resistance, and transistor, diode and battery test. Features automatic zero adjust, overage indication, and low battery indicator. Easy to read LCD readout and comes with 32 inch long test leads. Great for testing battery drains and glow plugs.
7 Function Electric Multimeter Tester