ahhh it wont work in your 2002...i didnt see that before. Although, i would think if it plugs in right, it should work...I have read that it is the BCM that locks it. On my truck when i put the 6 disc changer in it....it would work until i actually started the truck. That is when the BCM would start talking to the radio and notice that it didnt have the correct VIN. Have you tried to install it in your truck? I am assuming it is in there now? Does it just say lock? I know on mine they just turned off the theftlock...that is what the instructions are for anyway.
2016 GMC Sierra 2500HD Denali
Extang Blackmax Tonneau
Weathertech floor mats and mud flaps
X-pel clear bra
SOLD 2004 GMC Sierra LB7