Target mode with iMac

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cabb2020 Author

Level 1

8 points

Target mode with iMac

I just wanted to verify that the following configuration should work to use iMac in target display mode.

2013 21.5" non-retina display iMac running High Sierra

2018 13" MacBook Pro running Mojave

using usb-c to thunderbolt adapter with thunderbolt cable for connectivity

Based on https://support.apple.com/en-us/HT204592

You can connect any of these older iMac models to another Mac from 2019 or earlier for use as an external display. Learn how to identify your iMac model.

27-inch iMac models introduced in 2009 and 2010: Use a Mini DisplayPort cable to connect your iMac to a Mini DisplayPort or Thunderbolt or Thunderbolt 2 port on the other Mac.
All iMac models introduced in 2011, 2012, 2013, and mid 2014: Use a Thunderbolt cable to connect your iMac to a Thunderbolt or Thunderbolt 2 port on the other Mac. If the other Mac uses Thunderbolt 3, you can use the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with your cable.

Target display mode requires macOS High Sierra or earlier on the iMac used as the external display. It does not work with macOS Mojave or later.

It seems like it should since iMac is not on Mojave, non-retina and between 2011-2014. It unclear in the article if MacBook Pro has an IOS limitation, but before I go to much farther, I'd like to verify that the above configuration is a supported target mode configuration. Thanks.

Posted on Jun 8, 2020 10:17 PM

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Answer 1

cabb2020 Author

Level 1

8 points

Jun 10, 2020 9:09 PM in response to BDAqua

The question then becomes how do I troubleshoot the issue. If I look at the system report/hardware/thunderbolt it appears that they can see each other, so cables are probably good. I've tried 2 keyboards to check command f2. I also used direct thunderbolt (no usb-c to thunderbolt adapter) between macbook pro mid 2014 running catalina and imac, still no joy. Is there the equivalent of /etc/messages or event log on imac I could check for errors. Any other thoughts? Thanks!

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Answer 2

cabb2020 Author

Level 1

8 points

Jun 10, 2020 9:17 PM in response to cabb2020

I've also tried this app. It turns of the bluetooth, but does not turn the display to target mode.

VirtualKVM. This was designed specifically for people wanting to use their iMacs in target display mode, and works especially well in situations where you want to connect a MacBook to the iMac. For example, if you plug your MacBook into your iMac via Thunderbolt, this extention will automatically switch the iMac to Target Display Mode, allowing you to use your iMac as a monitor. It also switches off the Bluetooth on the iMac, freeing up your mouse and keyboard to pair with your MacBook (assuming you're using a bluetooth keyboard and mouse). When you unplug the MacBook, the iMac's Bluetooth will be powered back up and the monitor restored.

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