2003 GMC Sonoma Owner's Manual - Page 181

Setting the Tone (Bass/Treble) AUDIO: Press and release the AUDIO knob until BASS or TREB appears on the display. Turn the knob to increase or to decrease. The display will show the bass or treble level. If a station is weak or noisy, you may want to decrease the treble. To adjust the bass and treble to the middle position, push and hold the AUDIO knob. The radio will produce one beep and adjust the display level to the middle position. To adjust all tone and speaker controls to the middle position, push and hold the AUDIO knob when no tone or speaker control is displayed. The radio will produce one beep and display ALL with the level display in the middle position. AUTO TONE (Automatic Tone): Press this button to choose bass and treble equalization settings designed for country/western, jazz, talk, pop, rock and classical stations. To return the bass and treble to the manual mode, press and release the AUDIO knob. Adjusting the Speakers (Balance/Fade) AUDIO: To adjust the balance to the right and the left speakers, push and release the AUDIO knob until BAL appears on the display. Turn the knob to move the sound toward the right or the left speakers. To adjust the fade to the front and the rear speakers, push and release the AUDIO knob until FADE appears on the display. Turn the knob to move the sound toward the front or the rear speakers. To adjust the balance and fade to the middle position, push the AUDIO knob then push it again and hold it until the radio produces one beep. The balance and fade will be adjusted to the middle position and the display will show the speaker balance. To adjust all tone and speaker controls to the middle position, push and hold the AUDIO knob when no tone or speaker control is displayed. The radio will produce one beep and display ALL with the level display in the middle position. 3-54