Electrical confusion 2000 1500

[michaelj239]

I have a 2000 silverado and have bought some new fancy mirrors with the turn signals and clearance lights and such. My issue is trying to get the clearance lights to work. I want them to come on when the truck is in reverse. At the BCM under the steering wheel, the green wire that everyone says to tap into, doesn't get power when i go into reverse. Backup lights work however. Then i said maybe ill hook it up so when i turn the cargo lights on they come on, dark blue with white wire in the BCM? nope. Get power there when cargo light is off but no power when cargo lights come on. Totally stumped here. Green wire is what everyone says the reverse lights come into the BCM as but I have no power! Any input would help me out a lot! Thanks guys.