MacBook Pro 2016 won't turn off screen when connected to external display

Discussion in 'MacBook Pro' started by bab5139, Nov 29, 2016.

  1. bab5139 macrumors member

    Nov 25, 2016
    Has anyone had an issue with their mac book pro 2016 not displaying the screen saver or sleeping the screen while connected to an external display. Mine sleeps the screen normally when not connected. When connected to one monitor it keeps both the laptop screen and the monitor on forever. If two monitors are connected, 1 external monitor will sleep, but one of the screens and the laptop screen stay on forever.
  2. Menopause macrumors 6502a


    Feb 26, 2011
  3. sn0warmy macrumors 6502a


    Mar 26, 2009
    Denver, CO
    My issue is intermittent. I have my tMBP connected to a 34" Dell monitor every day with the MBP lid shut. Most of the time the computer will go to sleep just fine and wake at the key press of my bluetooth keyboard. However, occasionally the computer/external monitor will fail to go to sleep, even when I'm gone for 2 hours.

    I haven't found the cause of this. Hopefully it's software related and can be fixed with an update.
    For reference, my 2015 15" MBP would ALWAYS go to sleep properly when setup in the same configuration with the same external monitor plugged in.
  4. Menopause macrumors 6502a


    Feb 26, 2011
    I have a 27" LG UltraFine 5K attached, I had a hunch that my 4-port non-powered USB hub was probably causing the sleep/wake issues, I just figured out it was an old Griffin Powermate plugged into my USB hub that was causing this.
  5. ManuCH macrumors 6502a

    May 7, 2009
    Try issuing the following command in terminal:

    pmset -g assertions

    If you have value >0 right of the "PreventUserIdleDisplaySleep" line, there you have it. On the bottom it should list what exactly is preventing the display from going to sleep and you can try solving it from there.
  6. Exile714 macrumors 6502a

    Jan 14, 2015
    What display cable are you using? My USB-C to DisplayPort doesn't have this problem.

    I did have a problem where the monitor wouldn't wake from sleep with the MBP using DisplayPort but I solved that with a monitor settings tweek.

    It always helps to be specific with these issues. Every detail helps, and people could try to replicate the issue if you gave a little more info.

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