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Pennock Author

Level 1

59 points

2018 MacBook Pro Target Display Mode Not Working

Has anyone successfully used Target Display Mode with the new 2018 15" MacBook Pro? We just purchased one last week, and I am trying to use a late 2013 27" iMac as a second monitor via Target Display Mode.

When I hit command-F2 it does try to switch over, however the screen either a) remains black b) shows my screen but blinks every other second c) shows the screen but it's static-like and has crazy zig-zag colors across the background and flashes and such.

I have done all the recommended trouble shooting steps per the knowledge base article and am wondering if this is a problem with the new MacBook Pros. It is very frustrating to not be able to work on my brand new computer; I need the larger monitor for graphic design.

Both have latest versions of High Sierra. I have tried two different Thunderbolt 2 - USB-C adaptors. I have tried two different Thunderbolt 2 cables. One I have used for four years so I know it works. I have reversed the cables and tried all the different Thunderbolt ports on both machines. I connected them using Target Disk Mode to transfer my data and that worked.

I reset the SMC and zapped the PRAM. I booted in safe mode on both machines and then restarted. I have spent a good bit of time on this, but since this is a work machine I can't keep wasting time on it as I need to actually get work done, which unfortunately means still using the older iMac.

Any other thoughts?

MacBook Pro (15-inch, 2018)

Posted on Aug 2, 2018 7:53 AM

224 replies

TayDC

Level 1

28 points

Aug 3, 2018 5:39 AM in response to Pennock

I'm having the exact same issue. Trying to connect 2018 MacBook Pro 13" to a 2012 iMac in target display mode. It works perfectly on my 2016 MBP, but as soon as I plug in the 2018, my iMac display starts freaking out with the zig-zags you describe..really hoping that this is a software fix with the new models...

Pennock Author

Level 1

59 points

Aug 3, 2018 5:58 AM in response to Storm988

Whew, good to know I am not the only one! My gut told me this was a problem with the new MacBooks, that's why I was wondering if anyone else had tried Target Display Mode with them.

I was planning on contacting Apple when I get a chance, I just have to find the time at work.

I hope this gets fixed soon, my boss will not be happy when he comes back on Monday and sees me still using the older iMac after we spent all this money on new machines. We had bought two, but the other one is hooked up to a regular monitor and is working great.

TayDC

Level 1

28 points

Aug 4, 2018 7:15 AM in response to Pennock

Same here, Apple is calling me back early next week and apparently with a senior advisor. Really hoping they will address the issue soon, as I would hate to have to return the machine only for them to release a software fix down the road.

And agreed, everyone should definitely contact Apple and raise the priority of the issue to them! I have also reached out to a couple Apple centric websites like 9to5mac to see if they would be interested in investigating the issue

Pennock Author

Level 1

59 points

Aug 6, 2018 5:54 AM in response to TayDC

Contacting some Apple news type sites is a great idea. Let us know if they get back to you!

I am hoping it is a software fix as well, our company did not budget to buy a new monitor as via the knowledge base articles it sounded like the Target Display Mode should be working with my 2013 iMac.

Also for people that don't want to call you can use the support chat feature. That is how I contacted them, it was more convenient for me while at work. It did not take very long.

danny m

Level 1

5 points

Aug 7, 2018 1:13 AM in response to Pennock

I am having the same issue.

Connecting from a 15" 2018 MacBook Pro to a 2013 iMac via Apple Thunderbolt 3 to Thunderbolt 2 adapter and Apple Thunderbolt 2 cable.

The same setup worked fine with with my 15" 2016 MacBook Pro.

I suspect this incompatibility is emerging from an updated Thunderbolt system that is coming along with the new 8th Generation Intel processors. Hopefully this can be resolved through firmware or software update and it isn't a limitation of the new Thunderbolt chip!

Pennock Author

Level 1

59 points

Aug 7, 2018 6:51 AM in response to danny m

Make sure you report it to Apple, the more people that report the better. I haven't heard back from them so I will be reaching out again for an update. I sure hope it's not a limitation of the new hardware!

TayDC

Level 1

28 points

Aug 7, 2018 7:16 AM in response to Pennock

It seems like this affects all 2018 models by the sounds of it - which could be a good or bad thing, depending on if its software or hardware related. Apple is supposed to be calling me today to follow up so I will report back if I hear anything. Keep reporting the issue though, lets hope they issue a response!

TayDC

Level 1

28 points

Aug 7, 2018 7:59 AM in response to Pennock

Just got off the phone with a senior advisor, but they didn't have any answers for me. They kept telling me my 2012 iMac is incompatible with Target Display Mode...which it very much is, as it works perfectly with my 2016 MBP.

So I scheduled a Genius Appointment for Thursday - guess we will see what happens then

TayDC

Level 1

28 points

Aug 9, 2018 12:21 PM in response to Pennock

Well...just got out of my Genius Bar appointment, and the short answer was that Target Display Mode is "probably" not supported on the new 2018's. He showed me list of compatible iMacs and 2012 and 2013 are not/never were listed as compatible even with older MacBooks - which is untrue as I have 2012 iMac that works just fine with my 2016 MBP. So I have no clue what to do - I think I may have to return the 2018 MBP after all...

That being said he escalated my request to an Apple Engineer who will contact me with further explanation

Pennock Author

Level 1

59 points

Aug 9, 2018 1:40 PM in response to TayDC

Well that wasn't helpful, bummer. I wouldn't put much stock in what they said, as they were incorrect about compatibility based on the listed iMacs in Apple's own knowledge base article. Someone even posted the chart earlier in this thread.

When I talked to a senior advisor they told me my 2013 iMac should absolutely work in Target Display Mode, and that it should work with the 2018 MBP. I'm to talk to an engineer as well. I was told they may want me to do fresh OS installs on both machines as that was the only thing I hadn't tried to get it to work. I hope not, as that will be time consuming and I'm pretty sure it won't make a difference. I hope they consolidate all these reports somehow.

TayDC

Level 1

28 points

Aug 9, 2018 1:50 PM in response to Pennock

Yeah I didn't clue in when he was reading off the compatible iMacs - I think he got confused when it said "iMac (Mid 2011-Mid 2014)" He read it as 2011 AND 2014, when it clearly means from 2011 to 2014. So hopefully that is a good sign and the Apple engineer that should be emailing me clarifies things..fingers crossed

b3ntup

Level 1

4 points

Aug 12, 2018 2:54 PM in response to Pennock

I have the same issue, but 13" 2018 MBP and 27" late-2012 iMac, Apple Thunderbolt 2 .5 m cable, Apple Thunderbolt 3 to 2 adapter. The most frustrating part is the intermittency of it. It seems like I can work for a bit, and then it freaks out, gets increasingly worse, then starts working again.

Interestingly, it is always stable for about 50 seconds, and then freaks out for about 17 seconds. Like clockwork.

TayDC

Level 1

28 points

Aug 12, 2018 3:02 PM in response to b3ntup

I have the exact same set up as you - and identical symptoms. It is definitely trying to work, screen freaks out, then stabilizes for a bit, then back to freaking out. And the display settings are available on the MBP, which leads me to believe the feature was not removed - but instead a hardware or software issue, hoping for the latter as I have 2 days to return this machine...

Aug 12, 2018 3:48 PM in response to Pennock

I'm having the exact same issue with my new 2018 MacBook Pro 15" i9 and my late 2013 iMac as a target display. I've tested multiple apple thunderbolt adapters and thunderbolt cables but didn't work. I called Apple Support and the rep I spoke with was unaware of the issue and seemed to think it was specific to my computer, but I informed her of this thread. After a series of multiple tests and restarts and eventually an OS reinstall, I have the same result in target display- a flashing unstable screen on the iMac. For what it's worth, I connected my iMac to a 2015 MacBook Pro thunderbolt 2 and target display worked perfectly, so I know the issue is with the 2018 MacBook Pro. Very disappointing after spending a small fortune for this machine....

Pennock Author

Level 1

59 points

Aug 13, 2018 6:08 AM in response to Pennock

More people have clicked the 'I have this question too' button, which is good! Keep up the reporting to Apple! I also directed their support staff to this thread. If we keep it up they will recognize this is a universal problem with 2018 MBP's and maybe release an official response and hopefully can fix it!

There are people who want to return these machines because of this, so I would think that's a big deal to Apple. As more people buy them it's only going to get more widespread. My expensive new laptop is just sitting here unused as I need the big screen to work 95% of the time, it's been weeks now of wasted money. I would think they should have enough reports by now to start to realize this is a real problem.

2018 MacBook Pro Target Display Mode Not Working