2006 Avalanche - No Power to Aftermarket Head Unit

[Austin Boston]

Not getting power to an aftermarket head unit in a 2006 Chevy Avalanche.

I used a multimeter to test the yellow 12V constant circuit which showed ~12V, so far so good.  Then I tested the red 12V switched circuit with the car running and got no reading, so it looks to me like the problem is something to do with this circuit. I checked the radio fuse and it was not blown. I thought perhaps there was a separate fuse for the switched radio circuit but I can't figure out which it would be. I've tested almost all of the fuses related to ignition or accessory and all are good.  I also threw a different head unit in there just to rule out that it was a bad unit (even though it should've still shown voltage on the switched circuit when the car was running). Looking for advice on where to go next in my diagnosis. Thanks.

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