LG UltraFine 5K not auto adjusting brightness with MacBook Pro

I'd like to revisit this. Can someone at Apple confirm that this monitor should / should not automatically adjust brightness? Thanks

pedro d wrote:

Check out page 25 of the LG UltraFine Owners Manual. "The ambient light sensor operates in accordance with Mac OS. Some Mac OS doesn't support the display ALS(Ambient Light Sensor). You can also adjust the monitor brightness by controlling the menu or hot key of a host manually."

This is the first time I hear that it works for anyone or even that it should be able to work. At least it has never worked with my 2017 MacBook Pro with any software version including the latest and I know a lot of other people have the same problem. The checkbox just doesn't show up and the monitor never auto adjusts.

I just lived with it for a year until I finally got around building a tool that synchronizes your LG Brightness level with your MBP's built-in display. You can download it for yourself if you like (it's free and open-source and the binary is virus-scanned by Apple, e.g. notarized): https://github.com/ocjvandijk/Brightness-Sync

Now personally I'm really interested to hear from someone that actually got it working without some third-party tool. That would be the best of course.

Hi gersh10,

Thanks for coming to Apple Support Communities for help with your auto brightness syncing on your LG UltraFine 5k and MacBook Pro.

Check out page 25 of the LG UltraFine Owners Manual. "The ambient light sensor operates in accordance with Mac OS. Some Mac OS doesn't support the display ALS(Ambient Light Sensor). You can also adjust the monitor brightness by controlling the menu or hot key of a host manually."

Is your MacBook updated? How to update the software on your Mac.

Have you tested this issue in safe mode or a new user account? Please see: Use safe mode to isolate issues with your Mac and How to test an issue in another user account on your Mac

Also be sure and see: Get help with video issues on external displays connected to your Mac. It's possible that the issue is with the cable or you need a firmware update from LG. "Firmware updates for the LG UltraFine display are managed using LG Screen Manager. Search for it on the Mac App Store, and run the app periodically to check for and install firmware updates" from: Use the LG UltraFine 5K Display with your Mac.

Have a great day!