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

Top-ranking reply

PENG ZHAO

Level 1

18 points

Posted on Sep 12, 2018 1:15 PM

hey guys, just want to confirm that I used Belkin Thunderbolt 2 Express F4U085TT to connect my MacBook Pro 2018 with an iMac 2013. The iMac can be used as a target display. No flickering, no dark display. It just worked flawlessly.

Basically, you need a Thunderbolt 3 to Thunderbolt 2 adapter and the Thunderbolt 2 cable that comes with the dock to connect your MacBook Pro to the dock. then need another thunderbolt 2 cables to connect the dock to the iMac. I know it sounds stupid but it works.

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224 replies

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 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.

Aug 15, 2018 9:27 AM in response to Pennock

Same problem here 😟. Something of note: I have a belkin hub, and the idea popped in my head. What if I connect both my iMAC and my 2018 MacBook Pro to the hub, maybe Target Display Mode will work? I couldn't find the darn power cable to the hub, but after about an hour of searching I found it. The suspense was killing me, because I really need it and want it to work. Good news and bad news. The good news is, target display mode works just fine. The bad news, it only works for a few minutes before it starts to flicker. But, having both computers connected to the hub delays the flickering, just a tad bit. Interesting

Aug 17, 2018 6:25 AM in response to Pennock

I have the exact same problem. Brand new 2018 MPB (13" w/touchbar) and a mid-2011 iMac. I have been successfully using the iMac as a secondary monitor for a few years with my mid-2015 MBP (and still using since i can't use my new 2018 as I need a secondary monitor for work). Both running High Sierra 10.13.6. I get a black screen on the iMac and after few seconds the 2018 MBP screen starts freaking out turning on and off. I contacted Apple support right away and they confirmed everything in my setup was correct and should work (did all the restarts with them on the phone). The had no answers for me so I have been searching for a solution for two weeks (and like others I don't really have time as I need to be working. I'm self-employed and time is money. I also really need to sell the old laptop to help pay for the new one). Hoping for an answer soon.

bigron82

Level 1

4 points

Aug 17, 2018 2:16 PM in response to Pennock

I've got exactly the same issue with a new MBp 2018 and a mid 2011 iMac. Both running high sierra, have tried different cables etc

Having reported to apple support and trying to get pushed to an engineer

Aug 21, 2018 7:24 AM in response to RustyBensh

But UpTab is a Mini Display Port Adapter. Would not work for IMAC Target Display Mode, because it needs a thunderbolt connection.

Grant Bennet-Alder wrote:

Thunderbolt 3 to Thunderbolt 2 Adapter
Maybe this one works.

No, no, no ...

Those ThunderBolt 3 to 2 adapters do not present ANY directly-usable display interfaces.

To connect to a Mini-DisplayPort display, you must use an adapter specifically for the conversion you need, and it must be complete in ONE adapter.
...

So for target display mode thunderbolt provides the only working display mode solution 😉 No specifically adapter here.

Pennock Author

Level 1

59 points

Aug 31, 2018 5:55 AM in response to pg@cfit

pg@cfit - If you have the time and are able to take your machines to a store for them to look at it, it may be worthwhile. Maybe it would help prove that this is a problem with the new laptops and therefore get Apple to fix it. So far they will not acknowledge it as a problem and just keep putting us all through the same troubleshooting steps that do not work. You'd think someone in support would have consolidated all our reports by now!

There are around 100 people just on this one thread that clicked 'I have this question too' which means there are many more out there with this issue.

wadeopgh

Level 1

4 points

Sep 7, 2018 12:35 PM in response to Pennock

I'm having the same issue, 2012 27" iMac connected to new 2018 MBP 15". I purchased the Thunderbolt 3 to Thunderbolt 2 adapter ($50). This works flawlessly with my 2013 MBP but not so much on the new machine.

My iMac will blink for about 20 seconds then gets all weird grainy while blinking and making a horrible noise then the screen goes black.

All my cables are thunderbolt and have triple checked the compatibility of everything. When I hook up the older MBP

it just works. Come on Apple $2500 on a new machine and it just does not work 100%...

I spent all afternoon trying to get this working and I'm sure this affects a bunch of your customers as they require multiple monitors to do their work. Many of which have and slightly older iMac that works great as a monitor.

Sep 11, 2018 7:26 PM in response to Pennock

I have the same problem. I've logged a support ticket with Apple.

I have a 2018 MBP.

iMac Mid 2011

Both are running High Sierra 10.13.6

Thunderbolt 2 cable

USB-C to Thunderbolt 2 adaptor

All genuine Apple parts.

The cables work perfectly for data transfer in Target Disk mode.

The cables (excluding adaptor) work perfectly from an old MBP.

I've tried resetting the NVRAM and SMC. Neither work.

Symptoms: Screen flashes on iMac, display preferences on new MBP show it is connected, but then disconnects after a short while. You can see the mouse move on the iMac and the wallpaper of the MBP displayed on iMac in between flashes. Then iMac screen goes black.

Following this to find the solution....

Sep 13, 2018 1:49 PM in response to Pennock

Pennock,

Nice to hear from someone in the cyber yonder.

Let's see what they say tomorrow. I can't really hang around for X amount of days/weeks/months while Apple may or may not fix this... who knows, maybe the tech is even impossible to implement? Or they want to serve a death warrant to display ports much like firewire seems to have now been ditched? While I would prefer not to sell my iMac and not buy a Dell XXX or ASUS ZZZ to do the same task it may be more prudent to go this way and get to work properly. (Or borrow a spare HDMI monitor for a while).

avi136

Level 1

4 points

Oct 2, 2018 5:54 AM in response to Pennock

I have the same issue.
Macbook Pro mid 2018 i9 32Gb 15" (OSX 10.14)
iMac mid 2011 21.5" with thunderbolt connection (OSX 10.13.6)

Apple thunderbolt 3 to 2 apple original.
I can't use my iMac as a second display

From my MacBook Pro late 2013 to iMac mid 2011 it's working fine (so the thunderbolt cable is OK)

keatch

Level 1

4 points

Oct 3, 2018 11:05 PM in response to Pennock

I had this exact same issue and after trying every possible cable and adapter combination I contacted Apple support. They took me through a bunch of troubleshooting and eventually escalated it to engineering. They were also unable to find a solution. After a couple of calls with engineering, I just bought another monitor and stopped trying to get it to work.

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2018 MacBook Pro Target Display Mode Not Working