The wiring harness allows you to hard wire a standard aftermarket car or truck radio to the connector in the cab of the tractor making it plug and play without the hassle of splicing and soldering wires directly to the cab of the tractor. Red: +12v ignition/Accessory Yellow: 12v Battery/Radio memory Black: Ground Blue: Power antenna Blue/White: Amp turn on Green: Left Rear + Green/Black: Left Rear - Purple: Right Rear + Purple/Black: Right Rear - White: Left Front + White/Black: Left Front - Gray: Right Front + Gray/Black: Right Front -