Car stereo wiring need't be a job that you need to call in a professional for. Although Android 4.4 car stereo wiring can be complex, these handy tips should help you along your way.

Tip 1 - Use a Wiring Interface
If your car has existing steering wheel mounted controls, you will find it easier to use an already pre-built wiring interface that can simply be plugged in to the mounting plate. 

Tip 2 - Use the Right Wiring Harness
Sadly the electrical connectors in cars aren't standard fittings. Most car models have their own style of electrical connectors so in order to fit a car stereo correctly, you need to make sure you use a wiring harness that is right for the make and model of your car. Using a wiring harness will eliminate the need to cut the wires in your car in order to fit a new stereo. 

Tip 3 - Follow the Radio Color Code
Each stereo will have its own wiring and color code information that goes with it. For each speaker and control, an Android car DVD will have a different colored wire and wire pin. A list of these colors will generally be provided by the manufacturer. If you are wiring a stereo without using a wiring interface and harness then make a note of the color code together with the color code of the new stereo. 

Source: Doityourself.com