"UQ3" is "Performance Enhanced Audio" which means you do have a stock amplifier that is labelled in the Factory Service Manual as the :Low Frequency Audio Amplifier." This amplifier is located below the glovebox. To access it remove the glovebox door (five 7mm screws along the base of the door) and you'll see it on the bottom of the cavity, it's a gray plastic box with a blue connector on the driver's side of the box.
First check the 10 amp fuse that powers the amplifier which is located in the fuseblock under the hood by the battery.
