I use an FM modulator that plugs into a power port (cigarette lighter). Unfortunately on my 08 Trailblazer LT, both ports are hot all the time. What I did was pull fuse #29 RAIN in the rear seat fuse panel and insert an ATM Add-A-Tap placing the fuse in the tap. I then did the same for fuse #48 AUX PWR. I then tied each together after removing the butt connector from one of the taps. Make sure you find the hot side of fuse #29 and the load side of fuse #48, You also have to check continuity to determine which lug on the tap goes to the wire THROUGH one of the taps fuses. This gives your Aux Ports switched ACC and ON, not RAP!