To adjust the backlight on the Garmin Astro 430 please follow these directions.
  1. Go to Main Menu
  2. Select "Setup"
  3. Select "Display"
  4. Select "Backlight Timeout"
  5. At this stage you can adjust how long your backlight on your device stays on before it dims itself. The options are: always stays on, 15 seconds, 30 seconds, 1 minute, 2 minutes.
Note: The longer the backlight stays on, the faster the batteries in the device will die.