The vehicle circuit usually consists of a power supply circuit, a starting circuit, an ignition circuit, a lighting and light signal device circuit, an instrument information system circuit, an auxiliary device circuit and an electronic control system circuit.
The power circuit, also known as the charging circuit, is a circuit composed of batteries, generators, regulators, and charging indicating devices. Electric energy distribution (power distribution) and circuit protection devices can also be included in this circuit.
The starting circuit is a circuit composed of a starter, a starting relay, a starting switch and a starting protection circuit. The device for starting and preheating under low temperature conditions and its control circuit can also be included in this circuit.
The ignition circuit is unique to gasoline engine vehicles. It consists of ignition coil, distributor, electronic ignition controller, spark plug and ignition switch. The electronic ignition control system controlled by the microcomputer is generally included in the engine electronic control system.