Before using your DMM plug the two probes into their appropriate places on the meter. The black probe will plug into the common port labeled “COM.” The red probe will plug into the “VΩµmA” port for most testing.
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.