TS-8390-49XX Backlight
From embeddedTS Manuals
The backlight is controlled through the sysfs in /sys/class/backlight/backlight_lcd.27/. This allows 8 levels of brightness:
# Turn off backlight
echo 0 > /sys/class/backlight/backlight_lcd.27/brightness
# Backlight on low intensity
echo 3 > /sys/class/backlight/backlight_lcd.27/brightness
# Backlight on full intensity
echo 8 > /sys/class/backlight/backlight_lcd.27/brightness