switched power outlet, 2007 silverado

Hi guys...first post, so if it has been answered already, please be gentle.. I have a 2007 Chevy Silverado Ext Cab, LT1. I want to switch the power outlet with a 40A relay (because that's what I had on hand). I know how to wire the relay and make the new circuit but I need to know where I can pick up a switched power source to de-energize the relay. I have heard that the new radios don't use a switched power input any longer. (Something about a data bus talking to the radio for the delayed power off feature) Can someone tell me where I should look for a switched +12V for my circuit?.....thanx....

oh wait..theres more..it may also be yellow..and also can be found at the BCM, light green plug, pin # 21Custom Audio

Lynbrook NY

ASE/MECP master certified

Much appreciated. I'll check this out next weekend....hopefully!

Yellow wire...light green plug....worked like a champ....here is another wiring gotcha...the 2 outlets in the dash are supposed to run off the "Aux Pwr" Fuse. (according to the owners manual) There are 2 RED / White wires on back of the fuse box for this fuse. Only one of those outlets is powered from this fuse. The back of the fuse box has 2 RED / whites but when I yanked the fuse only the passenger side power outlet went dead. I figured ...OK maybe the drivers side outlet is powered off the "Aux2 Pwr" fuse....this only killed the power outlet in the center console which is is the one that I switched with the ignition through the relay...I never did find where the Driver's Dash power outlet is fused. I don't know where the second wire from the "Aux Pwr" is going. I assumed (yeah...I know not to) that one would go to one outlet and one to the other....but this is not the case. I appreciate your response regarding the acc. power wire. It was a HUGE help....redhawk.