Review on ASC Audio Car Stereo Wire Harness and Antenna Adapter for Buick Chevrolet GMC Hummer Isuzu Oldsmobile Pontiac - Fits 03-06 Silverado, Tahoe, Suburban, Sierra and More - Essential Details Inside by Drew Gengler

If you own a 2003 GMC Sierra DO NOT BUY! If you have a stereo system like this photo, it probably won't work. This harness connection fits, but most likely the wiring is in the wrong place. IF you have a GMC 2003 Sierra, go to Walmart and locate the Scosche GM2000A Wiring Harness. The Walmart website doesn't show this trailer, but if you go there you might get lucky. It's about $70 on the Scosche website / Walmart about $40-30. IT MIGHT be a little more money but it won't give you the headache it gave me. The 2000a harness had pretty much the same wire colors as my new Pioneer touchscreen stereo harness and it comes with a horn (beep if the door is open while driving). Hope that helps. (Oh, I blew a 10 amp fuse when I swapped out the stereo, so if it doesn't turn on, check that out).