Pioneer AVIC-S2 - Manual (Page 24)

3.2 Backlight
1. Tap the System Setting button on the Main Menu.
2. Tap the Backlight button.
3. Move the knob along the track bar to adjust the brightness of the backlight.
To darken the backlight, move the knob to the left. To lighten the backlight,
move the knob to the right.
4. Tap to save the changes.
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