The Electrical and Electronic System

The electrical and electronic systems are the brains of the modern automobile. For many
years, a car's electrical system contained only a battery, a battery charging system, and the lights or accessories on the vehicle. Today, almost every part of a vehicle is somehow powered by or controlled by an electrical or electronic system. Electrical and electronic systems control everything from engine operation to the temperature inside the car. Some of the electrical and electronic systems found in a typical automobile are the following:

• The battery and battery charging system
• The headlight and directional signal circuits
• The starter system
• The windshield wiper, horn, radio, and other accessory circuits
• The engine control systems

In the study units that cover the electrical system, we'll explore all of these systems to see how they work and how they're repaired. However, for now, you might like to know a few basics about these systems. First of all, it's important to remember that all automotive electrical systems operate on direct current (DC). Direct current is a constant source of electrical voltage. In other words, the source voltage is steady and doesn't vary. This constant voltage source is provided by the car's battery. Direct current is the same type of current that's used to power cordless appliances, as well as all other devices that run on batteries. In most automobiles, the battery voltage required to run the electrical systems is approximately 12 volts. (In comparison, a flashlight battery is about 1.5 volts.) A car battery is very similar in operation to a household battery, except that the car battery has a much greater voltage capacity.

All of the electrical and electronic devices in a car operate off the battery. However, the vehicle will also contain a separate electrical system that recharges the battery as the engine is running. This type of charging system usually allows a car battery to last for several years before it must be replaced.