Alternators typically use four wires which connect the ground, output, sensor and ignition indicator. These are known as the L, IG, S, B and F terminals. Alternators are ground either through their outer casing or a separate wire terminal connected to either the engine block or chassis. The output wire transfers current to the battery and is typically brown in color. The sensor terminal monitors voltage output, and the indicator receives voltage from the ignition switch.
Along with the battery, the alternator produces the electrical power needed to operate both the electrical components and engine of a vehicle. Alternators are mounted to the engine and are operated by a serpentine belt or powered by the crankshaft directly. Alternators produce alternating current through a process known as electromagnetism. A voltage regulator converts the power generated by the alternator to direct current.
There are four electrical terminals commonly located on the back side of the alternator. These terminals connect the alternator to the electrical system of a vehicle through a series of cables. As the engine spins the alternator, wire coils rotate around a fixed internal iron core, producing current. An attached voltage regulator determines the current power needs of the battery and electrical current is then transferred.