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Automatic brightness no longer works with mountain lion

I have a mid-2010 13" MBP that I upgraded to Mountain Lion via a clean install. Since the upgrade, the automatic brightness feature has stopped working and the laptop's screen brightness no longer responds to changes in ambient light level.

I've also noticed that I cannot deselect "automatically adjust brightness" in System Preferences – although I can clear the checkbox, as soon as I leave Display Preferences and go back, the box is rechecked. Adjusting the brightness using the slider or F1/F2 works as expected.

So far, I've tried resetting the SMC and PRAM, and using several combinations of energy and display settings, but no luck.


Is anyone else having this issue? Any ideas how I might solve it? Thanks.

MacBook Pro, OS X Mountain Lion

Posted on Aug 20, 2012 4:59 PM

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User profile for user: Community User
Community User Author

Aug 29, 2012 11:21 PM in response to evilxsist

Cheers for the link. Someone on your thread suggested it's caused by a System Preferences bug that's exposed by a case-sensitive filesystem. I reformatted my system drive as case-insenstive HFS and reinstalled 10.8.1. Problem solved, authomatic brightness on both screen and keyboard work as expected.


Thanks!

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Automatic brightness no longer works with mountain lion

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