in my 2008 base model pontiac grand prix, I have inserted a BOSS audio aftermarket system. Everything is spliced in correctly, except for one thing. For my accessory ignition I spliced a 16 gauge wire to the red wire, and tapped it to the 25 amperage fuse called "radio/amp" in the fuse panel. However, the unit has constant power even when the key is not in the ignition at all. Then when I put the factory radio back in, it works just fine. Does this sound familiar?

 

"Look at the sign, we're in the wrong place...." (Bachman Turner Overdrive, 1975)

This is a 3rd Gen Camaro/Firebird community so you'll probably not get much detailed help.

However, the radio/amp fuse probably has 12-volts even with the key off. If you have a test light or volt meter you can confirm this yourself.

In general, most head units have two power requirements; one that feeds the clock and memory needs a constant on 12 volt source. The remaining stuff in the head unit needs a switched 12 volt source.