For 1990-2009 cars

The radio is used to adjust the vehicle's chime level. To change the volume level of the chime, press and hold pushbutton 6 with the ignition on and the radio power off. The 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 volume level will change from the loud level to normal, and NORMAL will appear on the radio display. Each time the chime volume is changed, three chimes will sound to indicate the new volume selected. Removing the radio and not replacing it with a factory radio or chime module will disable vehicle chimes.