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2018 MBP problem with target display mode on 2011 iMac

System info:

MacBook Pro (15-inch, 2018), 2.2 GHz Intel Core i7, 32 GB RAM, Mac OS 10.13.6

iMac (27-inch, Mid 2011), 2.7 GHz Intel Core i5, 16 GB RAM, Mac OS 10.13.6


Connection between systems:

Apple Thunderbolt 1m cable or 2m cable

Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter. This is plugged directly in to the MBP, which has no other peripherals plugged in.


Objective: Use the iMac in target display mode as an external monitor for the MBP.


(For background, my 2014 retina MBP, using the same cable, is able to use this iMac in target display mode just fine. So the iMac and the cable work for this purpose.)


I connect the cable to the iMac and to the adapter, which I plug in to the 2018 MBP. I press cmd-F2 on the iMac, which then enables target display mode. The screen changes to display the laptop's desktop, but then the screen flashes off and on, like it is hunting for the right resolution or it is struggling to detect the display.


Here's a short silent video of it happening: https://gfycat.com/gifs/detail/GloriousClutteredAntelope


According to https://support.apple.com/en-us/HT204592, this combination should work.


The cables and adapter are all Apple parts, so there is no third-party hardware involved here whatsoever.


I've tried both cables in all four ports on the laptop, and both ports on the iMac. I've tried it with the power cord removed from the laptop, and with it connected via a three-pronged power supply extension cord (from an older laptop) to the same UPS that powers the iMac. That should eliminate a grounding issue or something weird like that.


I've also reset the SMC on the MBP, since https://support.apple.com/en-us/HT201295 mentions it can fix some target display mode issues. That didn't fix it though.


Does anyone have any ideas or experience with a setup like this? I really want to use the iMac as an external monitor for this laptop, like I had been doing with the 2014 MBP.

MacBook Pro (15-inch, 2018), macOS High Sierra (10.13.6)

Posted on Aug 10, 2018 11:05 AM

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Posted on Aug 13, 2018 7:36 AM

Same problem, same specifications.


Did try all things, reset the SMC and NVRAM and that stuff. Tried out all ports and with/without power cable.

Nothing seems to work...


But it seems like there is an ongoing case with Apple. Keep tuned...


Having trouble getting Target Display mode to work with Apple's Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with new …


Target Display Mode: Flickering Screen

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11 replies
Question marked as Best reply

Aug 13, 2018 7:36 AM in response to adlerspj

Same problem, same specifications.


Did try all things, reset the SMC and NVRAM and that stuff. Tried out all ports and with/without power cable.

Nothing seems to work...


But it seems like there is an ongoing case with Apple. Keep tuned...


Having trouble getting Target Display mode to work with Apple's Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with new …


Target Display Mode: Flickering Screen

Aug 13, 2018 7:36 AM in response to adlerspj

Exact same issue here as well, but with the 13" MBP 2018 and my 2012 iMac - Had a genius appointment and was told that an Apple engineer will contact me with further info. This is definitely affecting all new models across the board (or so it seems) Call apple and escalate the issue to a senior representative so that Apple will take notice! Hoping for a software fix...

Aug 23, 2018 2:24 PM in response to adlerspj

Same problem here, can't use target display mode anymore without flickering and the display cutting in and out.


Not surprised though, the last four new MacBook Pros I've gotten have all had some sort of amateur issues that a company that controls the hardware and software should never let slip. Maybe Apple should just start shipping a nice big red "BETA" sticker with every piece of new hardware (and software) they ship. Maybe after the next trillion they'll be able to afford to hire QA people.

Aug 30, 2018 11:40 AM in response to adlerspj

I have the exact same problem.

Just got a 2018 MBP 15' 512 TB today and I'm using USB c - thunderbolt adapter etc. targeting my mid 2011 iMac.

Thought it was the cable or adapter, struggled and searched for a few hours, then I tried the using target display on my work's 2017 MBP 15' TB and it worked first time I pressed cmd F2.

Sometimes the iMac doesnt even try go into target mode with the 2018 MBP, sometimes it flickers and sometimes black screen.

I hope this is not hardware related, then we all have a problem using target display.


Apple please don't disappoint us, at least give us some feedback.

Sep 4, 2018 12:43 PM in response to BAS01

I also have this issue and l run a tech company and we have spent ALOT of money with Apple over the years. I just bought a 2018 MacBook pro and I have a late 2013 iMac. I've tried all the troubleshooting steps at the Apple Genius bar and on my own on the iMac: reset nvram, pram on imac and MacBook pro, re-installed the OS on my MacBook pro, Run Diagnostics on my MacBook pro, tried different adapters and cables, Nothing has fixed it. On the Phone I asked how do I get this resolved and the customer support rep suggested using apple.com/feedback and I told them NO.... I'm not interested in making a suggestion....I have Paid for Apple Care and with what I've spent now and in the past I want/demand this issue be tracked and I want a resolution because this is definitely an Apple issue. I have a Case Id with Apple, I'm told they have escalated it to their senior engineers and said I'll have feedback within 4 business days. So Stay Tuned... not sure if it's getting resolved but my company does social media consulting and if they blow us all off I'm returning my $5,000 MacBook Pro and starting a social media campaign to highlight Apple doesn't care about their Customers and Consumers need to consider Microsoft again.

Sep 10, 2018 1:57 AM in response to adlerspj

I have the exactly same problem too with almost same configuration as below:


System info:

MacBook Pro (15-inch, 2018), 2.2 GHz Intel Core i7, 32 GB RAM, Mac OS 10.13.6

iMac (27-inch, Mid 2011), 2.7 GHz Intel Core i5, 20 GB RAM, Mac OS 10.13.6


I just received the new macbook pro from my company and was very exciting only until I found this issue.

Apple, please fix this issue as soon as possible, I've lost my main workspace here.

2018 MBP problem with target display mode on 2011 iMac

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