03avalanche

hello everyone, i need help, i recently bought a 2003 Chevy avalanche Z71, when i bought it the radio didn't work, when i further investigated by removing the radio i found that the original wiring harness was clipped off, im guessing that someone failed to install an aftermarket radio or something? so i went online and purchased a generic GM harness, with a bunch of different colored wires that didn't match any of the original wires so i went to the scrap yard and pulled a harness from 03 Tahoe radio, its the same colored wires and thicknesses so it should be the correct harness, now the question is, if i bring it to car toys and have them wire it up will my radio work again? will the trucks computer not communicate with the radio correctly and mess it up more? please respond with answers to these questions, or tips on how to make my radio work again, shoot me an email if you can, im really busy with school and wrok and its hard for me to open this form, thank you