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.
You can determine the amount of current being used and charged on your tractor’s system by placing the meter in-series with the circuits of the tractor. To do this: first remove your red probe and plug it into the 10 amp Max port on your DMM. Then set your DMM to DC Current with the range of 10 amps. Now you unplug the wire going to your ignition switch’s “B” terminal. By clipping alligator clips to your DMM probes you can now connect one probe to the “B” terminal of your ignition switch, and your other DMM probe to the wire that normally goes to “B” terminal on the ignition switch. Now when you run your tractor the current will flow through the meter and your DMM can give you a reading. It will tell you how many amps are flowing through your system.
A circuit is a closed loop of wiring and components beginning at the positive side of the battery and ending back at the negative side of the battery. This loop is often closed using a common ground. Electricity only flows when a circuit is a closed loop. If the loop is open no electricity flows.
Most of the circuits in lawn and garden tractors use low amperage with the exception of the starting circuit. The wiring also only runs a short distance. I recommend using 6 AWG wire for the high amp starting circuit, and the negative side of the battery to common ground connection. All other wires can be 16 or 14 AWG. The easiest and most effective way to make all of the connections is by using nylon wire crimp connectors. Nylon wire crimp connectors are more durable than ones made from PVC. They are also easier to install than soldered connections. The most common crimp connectors you will use are spade and ring connectors.