GM Service Manual Online
For 1990-2009 cars only

Chime level adjustment is only available on RDS radios. The radio is the vehicle's chime producer. To change the volume level, press and hold pushbutton 6 with the ignition on and the radio power off. The chime volume level will change from the normal level to loud, and LOUD will appear on the radio display. To change back to the default or normal setting, press and hold pushbutton 6 again. The chime level will change from the loud level to normal, and NORMAL will appear on the radio display. Removing the radio and not replacing it with a factory radio or chime module will disable vehicle chimes.