The centerpiece of your car's entertainment system is the car radio. You should know how it interacts with your car's speakers and other electronics before you yank it out.
Almost every car ships with a radio. Most car radios also include a tape deck or a CD player, and some current vehicles still come equipped with both. Many new car radios are also capable of controlling a multi-disc CD changer or connecting to a satellite radio. Because the car radio is really a master control for all sorts of electronic entertainment devices, it is often called a head unit.
General Motors, BMW, Honda, Saab, Ford, and car company you can think of, all manufacture different head units for their vehicles, and they often use different units depending upon the year and vehicle model. Each car company has its own proprietary interface for CD changers, and there are no real standards. Figure 2-1 shows a simple OEM (original equipment manufacturer) head unit.
Figure 2-1. A CD and tape player head unit
There's rarely an opportunity to upgrade the head unit for a better one from the dealer who sold you the car, but the vast majority of cars can accept aftermarket head units. These range in price from under $50 for a simple model to upwards of $2000 for a fold-out touchscreen that can interface with DVD players, CD changers, and satellite radios, and that ...