Cannot adjust brightness on secondary Thunderbolt Display (daisy-chained on MBA)

Discussion in 'Mac Accessories' started by SouthPaW12, Sep 16, 2014.

  1. SouthPaW12 macrumors newbie

    Mar 3, 2008
    I have a mid-2013 MacBook Air powering two Thunderbolt Displays. I have my MBA plugged into the first display, and then I'm daisy-chaining the second, exactly as Apple intends.

    Both monitors turn on, are responsive, etc., but there is no brightness control for the secondary display. I physically swapped positions of these displays to confirm that Display #2 wasn't defective, and it is not. The primary display goes from max brightness to min brightness without any qualms, but the secondary one will not adjust at all, and instead remains very dim throughout use.

    I have tried Control + F1/F2 (using Mavericks, OS X 10.9) and it does absolutely nothing on the secondary display.

    You can see that even in System Preferences, there's no Brightness Slider for Display #2, regardless of where I set the Dock. Image is here:

    Any help would be greatly appreciated!
  2. SouthPaW12 thread starter macrumors newbie

    Mar 3, 2008
    And a reboot while everything was docked and connected solved it. Control + F1/F2 now controls brightness properly on the secondary display.

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