To measure voltage on a battery for example you first turn your meter to DC Voltage. Place the red probe on the positive terminal of the battery and place the black probe on the negative side of the battery or on a common ground. Your voltage will display on the screen.
Measuring voltage is one of the most common tests a tractor mechanic will conduct as he troubleshoots a system. The presence of the correct voltage will determine if a component is functioning correctly or not. A common voltage test will be of the battery. A healthy battery should read about 12.5 volts, and a battery that is being charged should measure between 13 and 14.5 volts.