Answer to: Location of radio amplifier?Is the antenna plugged in? Update (10/24/2017): I have a 1999 yukon denali with RPO code Y91... I completely removed it cause I think they are crap. And installed after market amp HU and speakers including sub of course. But if the radio is not working.. make sure antenna is plugged in or if you have a powered antenna make sure that remote turn on wire is hooked up.