Ambient Light Sensor Testing
The ambient light sensor brightens the display when using the iPhone in bright light environments, and dims the display in low light. To test this sensor, do the following:1. Verify that the Brightness setting (Settings > Brightness) is set to Auto-Brightness ON, and that the Brightness level is set near the middle of the slider
2. Press the Home button to return to the Home screen, and then press the Sleep/Wake button to lock the iPhone
3. In a bright light environment, cover the top third of the iPhone to block the light, and then press the Sleep/Wake button or the Home button to wake the phone. Slide the slider to unlock the phone
4. Notice the brightness of the screen and application icons; they should be dimmed
5. Remove the iPhone cover from the top of the display and in a few moments the display will brighten
