2003 Chevrolet Tahoe, Aftermarket Stereo, Accessory Wire

Can only get aftermarket head unit to come on with a jumper from the yellow (power wire ) to the red (accessory) wirePaul hoffman

You have a couple choices. Return the harness and get the proper one. Metra AXDICL2 will provide a retained accessory output. This will keep the radio on until you open the drivers door, just as your factory radio did. Or, if your AC control has 2 separate plugs on it and one harness has larger wires than the other, you can tap into the brown wire of the harness with the larger diameter wires. Or use the bundle of red wire and the fuse tap that came with the harness you have and run it to and tap into the Windshield Wiper fuse in the fusebox at the end of the dash on the drivers side. It is labeled WSW on the diagram inside the cover on end of dash.Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

https://www.gmupfitter.com/wp-content/uploads/2021/05/2005_LD_CKFullSizeElectrical.pdf   pages 49 and 52 although one might peek around.