The stereo wiring diagrams gives a detailed listing of all the wire colors and the purpose of each wire that connects to the plug in the radio. Keep a note of the printing on each wire in the stereo harness and the adapter.
Most stereos come with the harness wiring diagram printed on the label fixed on the top of the unit. The diagram may also be available in the manual. Color coding is mostly used to simplify the wire matching process. The typical wiring colors include red, black, yellow, blue and orange, and a few wires are multicolored.
After categorizing and understanding the various color codes of the wires, the next step is to identify the purpose of each wire on the wire harness. In most cases if not all, the constant power wires are red, remote wires are yellow, and the ground wires are black in color. The speaker wires are striped and multicolored. The blue wire in the harness is for the power antenna and the orange wire is for the head unit illumination.
Once the person reading the wiring diagram understands the function of each wire, the last step is to connect the corresponding wires of the stereo to the respective wires of the main unit.