Macbook Pro USB-C Display not recognized anymore

Question

Level 1

11 points

Macbook Pro USB-C Display not recognized anymore

Hi,

my external Display a LG 27UD88-W connected via USB-C to my MacBook Pro 15" 2016 was working with some problems in the last 2 months. Sometimes the display stayed black and I had to restart my MacBook.

Since yesterday the display stays black, it recognizes that it is being connected (wakes up), but goes back to sleep (no signal). Sometimes but not always, after connecting the Display, I get the following error message:

I tried without success:

Unplug USB-C cable
Disconnect and reconnect the Display power cable
Install all macOS updates (not required, already have the newest version)
Restart the MacBook with the Display connected
Restart the MacBook without the Display connected
Reset NVRAM
Reset SMC
Reset Display to factory settings

MacBook Pro (15-inch, Late 2016), macOS Sierra (10.12.5), LG 27UD88-W Display

Posted on May 21, 2017 4:39 AM

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Answer 1

tjk

Level 9

51,192 points

May 21, 2017 6:44 AM in response to Tobist

You've tried everything I would, except running in Closed Display Mode/Clamshell, and booting into Safe Mode: https://support.apple.com/en-us/HT201262.

If neither helps, then bring the Mac and display and connecting cables and power adapter to an Apple Store “genius” bar for a free diagnosis, and if there's a hardware issue, you're still in warranty period, so it should be repaired for free: https://support.apple.com/contact

Backup your HD before you go, as you always should.

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Answer 2

Nov 24, 2017 7:50 AM in response to Tobist

I've 2 USB-c cables one from Apple one from LG, neither work now after a few months of use.

What cable does work?

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Answer 3

Tobist Author

Level 1

11 points

May 25, 2017 3:33 AM in response to tjk

Alright I tried this without success, so I went to a friend with the same display and MacBook (we bought it together). We tried every combination and surprisingly it was the cable (his laptop and display does not work with my cable, my laptop and display works with his cable). The cable is only 3 month old and is the original cable that came with the LG display and I hardly put it in and out.

Anyway if someone has the same issues they might consider that it could be the cable too.

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