Dead USB-C connection between macbook pro and LG 27UD88 monitor

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Dead USB-C connection between macbook pro and LG 27UD88 monitor

Hello,

I have an early-2017 macbook pro, which I have connected to an (also early 2017) LG 27UD88 monitor via a USB-C connection. On Feb 28th 2019, the monitor suddenly became unresponsive via this connection. When I plug in the cable there is no response from neither the monitor nor the laptop. Connecting to the monitor via hdmi still works fine, but the downside is that in this mode the monitor does not provide charge and ethernet connection to my laptop, so I need to plug two more cables to the laptop. To be clear, it is not just the picture which is dead, but there is also no charge or ethernet via the USB-C.

I have contacted LG support. First they told me to download new monitor drivers that they amazingly put online on the same day my monitor connection went dead. I went to their website and downloaded all the software that appeared on 28/02. This is actually not drivers, but rather applications for onscreen control, dual controller, and truecolor, i.e. for manipulating settings on the monitor. Just in case, I installed all this on my mac (as well as the last driver update from 2018), but it makes no difference for the dead connection.

I went back to LG support and they now tell me to contact Apple support for help :(

It sounds a bit unlikely that the problem is on the mac side, but what the ****, I guess there is no harm in asking. I get the feeling that they're just stalling ... the guarantee for my monitor runs out in a month 😖

MacBook Pro 15", macOS 10.14

Posted on Mar 4, 2019 5:49 AM

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Answer 1

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BDAqua

Level 10

239,351 points

Mar 4, 2019 9:05 AM in response to joakim160

First thing to try...

The Solution to No-Cause Random USB Failure on a Mac: Resetting SMC

So, you’re confident a USB port is the problem and not the device itself? The first thing you should do is reset the Mac SMC, a simple process which is slightly different depending on the Mac hardware.

You can learn how to reset the SMC on all Macs here in our detailed tutorial. For those with a MacBook, MacBook Pro, and MacBook Air, all you need to do is this:

Shut down the Mac and connect the power cable

Hold down Shift+Control+Option+Power concurrently for a few seconds, when the light on the power adapter blinks or changes colors you’ll know SMC reset is complete

Release all keys at the same time

Boot the MacBook Pro / Air by hitting the power button as is typical

The USB ports on the MacBook should now work just fine, which you can confirm by connecting the USB device as usual and checking to be sure that it works – if it’s still not working, try another USB port, and try another USB device.

Another Fix for USB Not Working: the NVRAM Reset

Sometimes resetting the NVRAM / PRAM on a Mac can help resolve the USB port failure as well, since NVRAM holds various data about keyboards, mouse, trackpad, and other USB components. Here is how you can perform the NVRAM reset on a Mac to see if this resolves the USB failure:

Restart the Mac, and immediately hold down Command + OPTION / ALT + P + R keys together – keep holding the keys down until you hear a sound and see the screen flash, it may take a few seconds

The Mac should make a chime sound again, then let it boot as usual

When the Mac boots back up again, USB should be working as usual.

If, after an SMC reset, and after an NVRAM reset, none of the USB ports are working, and no USB device is working, something else is likely up with the Mac.

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Answer 2

Mar 4, 2019 9:31 AM in response to joakim160

Had issues with an HDMI connection to an LG display, and loading new firmware into the LG cured that. Also had to disable a color-related setting as part of that connection, though that was to get the initial connection working and that's clearly not the case here.

If you're not on LG monitor firmware 3.21 for 27UD88/27MU88, apply that. (Details)

As for what to do here? Patch the LG firmware to current, update Mojave to current if you're not already there, try the display while booted in Safe Mode, try the NVRAM reset and the SMC reset, try the Mac with a different LG of the same type, and try a different cable. Failing access to a similar-model LG monitor, try with a second USB-C-connected monitor. Finding another matching LG probably won't be easy, after all.

Prior to the end of the warranty and if you're still unhappy with the support, send a written notice of the issue to LG support and explaining or showing that whatever has (not) happened here and that this is prior to the end of the warranty, and copy the state attorney general or the folks in whatever the local oversight office might be.

You can certainly try the Apple Support folks, of course. They might know of some related issue in macOS.

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Answer 3

joakim160 Author

Level 1

8 points

Mar 5, 2019 3:11 AM in response to MrHoffman

Many thanks to you both BDAqua and MrHoffman!

I have tried your suggestions, save for plugging to another USB-C monitor and replacing the cable, since I unfortunately don't have access to either of these. All the other suggested fixes were unfortunately unsuccessful (NVRAM and SMC reset, safe mode, firmware update, OS update).

LG has now gotten back to me and gracefully offered me to buy another cable, so I will try that.

It's only 40 bucks for something that probably won't work 😒

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Answer 4

joakim160 Author

Level 1

8 points

Mar 18, 2019 4:18 AM in response to BDAqua

I got a Thunderbolt 3 USB-C cable for 30 euros, and it made no difference.

I then got back to LG's online service and they told me to contact Apple again !!

I then called LG up and after a lot of holds and redirections, I finally got someone who agreed there might be something wrong with the display. They sent someone to pick up the old display for repair and they left me a new display instead of the same type.

This new display works fine, with the old cable.

So there was clearly a malfunction on the USB-C port on the old display.

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