GMC Sierra Wiring Diagrams 1998 to 2016 - YouTube Click to view on Bing6:17This video will show you How to Access the Complete GMC Sierra Wiring Diagrams and details of the wiring harness. Diagrams for the following systems are included : Radio Wiring, Engine Wiring, AC wiring, ABS Wiring, Author: John AmahleViews: 5 1998 GMC Sierra C1500 Car Audio Wiring Chart - ModifiedLife Whether your an expert GMC Sierra C1500 mobile electronics installer, GMC Sierra C1500 fanatic, or a novice GMC Sierra C1500 enthusiast with a 1998 GMC Sierra C1500, a car stereo wiring diagram can save yourself a lot of time. 1998 GMC Sierra C1500 | Stereo Wiring Diagram 1998 GMC Sierra C1500. April 13th, 2014 Posted in GMC Sierra C1500. 1998 GMC Sierra C1500 Stereo Wiring Information. Radio Battery Constant 12v+ Wire: Orange Radio Accessory Switched 12v+ Wire: Yellow Radio Ground Wire: Black/White The stereo wiring diagram listed above is provided “as is” without any kind of warranty.