Thanks for the input guys! Since this is a one way trip, no going back to OEM in this car, I spliced into the harness and found the constant power, ground and illumination wire. I know the white/violet wire is supposed to be switched power, but it's on all the time or at least when I'm testing it. Any suggestions for pulling a switched power wire (from another accessory, the heater controls, etc. Or do I have to disconnect the battery or some other technique to reset whatever relay is keeping that wire hot?

Otherwise the radio will be on all the time.