MacBook Pro (14-inch, M6) Troubleshooting Keyboard Backlight Issues

1. Inspect the computer for liquid damage. Contact with liquid can short internal circuits and cause the keyboard to stop working.

2. Ensure that the ambient light sensor isn’t covered. It’s located at the top of the computer display near the camera. The keyboard backlight uses the ambient light sensor to illuminate in low-light conditions.

If the issue wasn’t resolved by following a support article or trying the quick troubleshooting steps, run these diagnostic and manual tests to help isolate the cause of the issue:

1. Press the Caps Lock key on the built-in keyboard to ensure that the indicator light illuminates. If the light illuminates, the keyboard is recognized by the logic board.

   • Note: Pressing the Caps Lock key on Apple keyboards may not immediately activate the Caps Lock function. The key must be held down slightly longer to activate the Caps Lock function. This is to prevent accidental activation of Caps Lock mode. This is normal behavior and doesn’t indicate a service issue.

2. If the built-in keyboard isn’t functioning, connect an external keyboard to the computer to continue troubleshooting.

3. Run the Mac Resource Inspector (MRI) diagnostic suite. This will activate the keyboard backlight.

4. Run the Keyboard diagnostic suite.

5. Check System Settings > Keyboard to verify whether the “Adjust keyboard brightness in low light” option is available and checked. Refer to Turn your Mac keyboard’s backlighting on or off.

6. The keyboard backlight is enabled only when the ambient light sensor detects low light conditions. Check System Settings > Displays to verify whether the “Automatically adjust brightness” option is selected.

7. Check ambient light sensor functionality by covering the sensor (on the display near the camera) with your hand to simulate a dark room. Check whether the display dims and keyboard backlight brightness increases. If the display or keyboard shows no change, display replacement is recommended.

8. Keep the ambient light sensor covered and use controls to increase the keyboard backlight level. If the backlight responds to manual controls, this indicates the keyboard backlight hardware is functional but may not be responding to the ambient light sensor. If the backlight doesn't respond to controls, this indicates a keyboard or logic board issue.

If the issue wasn’t resolved or isolated by following support articles or running diagnostics tests, refer to the computer’s repair manual to open and inspect the computer. A damaged or out-of-place part may be causing one of the issues.

Procedure

1. Follow repair manual procedures to remove the bottom case and disconnect the battery from the logic board.

2. Inspect internal parts and the enclosure for indications of physical or liquid damage, contamination, and burned or darkened areas. Inspect all relevant internal flex cables and connectors for damage or tampering, such as a film or foreign material blocking a connector.

3. Locate the keyboard backlight flex cable connector and verify that the cable is present and connected. If the cable is missing, it may be under the logic board. Remove the board to locate the flex cable.

4. Disconnect and reseat the keyboard backlight cable connection to the logic board.

5. Retest in low-light conditions to activate the keyboard backlight. Adjust the keyboard backlight using controls.

6. If the issue is resolved or inspection reveals no issues, complete the reassembly. If diagnostic results or inspection identified a faulty part, proceed to the Replace the part section. If the issue persists without identifying a specific part, proceed to the Replace the part section for logic board replacement.

Note: This section requires ordering parts and tools. Replacing a part may not resolve the device’s issue. You can find other service options at support.apple.com/repair.

If the issue wasn’t resolved or isolated by following the previous steps, replace the following parts for each relevant issue:

• For partial keyboard backlight functionality issues, replace the top case.

• If the ambient light sensor doesn’t activate the keyboard backlight but does dim the display, replace the top case.

• If the ambient light sensor doesn’t activate at all, replace the display.

• If the keyboard backlight doesn’t activate at all, or no specific faulty part was identified above, replace the logic board.

Repair completion

Depending on the part replaced, Repair Assistant may be available on the device to finish the repair. Learn how to initiate Repair Assistant.

Post-repair verification

Run the following diagnostic suites after the repair:

• Mac Resource Inspector (MRI) (to test overall functionality)

• Keyboard (to test the keyboard)

• Display Anomalies (to test the display)

After the repair is completed, turn on the computer and verify that the keyboard and keyboard backlight are functioning normally.

Note: This section requires ordering parts and tools. Replacing a part may not resolve the device’s issue. You can find other service options at support.apple.com/repair.

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