The one I got looks exactly like this
http://www.wilkinsonplus.com/measure...FJ6uMQ% 3D%3D but its made by corelectrics instead of rapitest. according to the instructions it does a dc voltage measurement, ac voltage measurement, dc current measurement, resistance measurement and a diode test. It has a 2, 20, 200, & 500 volt settings. So I set to 20 dc volts and touch the wires on the edis with the red probe but I'm not sure what you mean by putting the black probe in the com on the meter and the battery negative and red to v+?