2003 GMC Envoy Owner's Manual - Page 229

Rear Seat Audio (RSA) This feature allows rear seat passengers to listen to any of the music sources: radio, cassette tapes or CDs. The rear seat passengers can only control the music sources that the front seat passengers are not listening to. For example, rear seat passengers may listen to a cassette tape or CD through headphones while the driver listens to the radio through the front speakers. The rear seat passengers have control of the volume for each set of headphones. The front seat audio controls always override the rear seat audio controls. PWR (Power): Press this button to turn the rear seat audio system on or off. The rear speakers will be muted when the power is turned on unless you have a Base@ equipped vehicle. You may operate the rear seataudio functions even when the primary radio power is off. VOL (Volume): Turn the knob clockwise to increase volume and counterclockwise to decrease volume. The left VOL knob controls the left headphone and the right VOL knob controls the right headphone. 3-104