You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

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

Reply
224 replies

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 7, 2018 9:17 PM in response to Pennock

It seems that for now the target display mode is not working on the new MBPs, however there was a reference to an expensive hub that would allow the target display mode to work - what is that hub? There were also references on possibly daisy chaining the computer you were using TDM on to the other monitor so it could be used again does anyone have directions on how to do that?


Thank you

Sep 9, 2018 10:05 AM in response to Pennock

I'm having the same issue. Called Apple support and they asked me trying different debugging techniques, did not work.

After a couple of days they said the engineers had realized it's a common issue solely for MacBook Pro 2018 model and will release a firmware update fixing this. They just don't know when the update will be released.

Sep 10, 2018 6:35 AM in response to PENG ZHAO

PENG ZHAO wrote:


After a couple of days they said the engineers had realized it's a common issue solely for MacBook Pro 2018 model and will release a firmware update fixing this. They just don't know when the update will be released.


This is great news! All our reports are finally getting us somewhere. Anyone who hasn't reported their issue yet should do so and hopefully it will help get this firmware fix out sooner than later!

Sep 10, 2018 11:07 AM in response to Larszoon

Update: Just spoken with Apple Support. Number of scenarios discussed. And got the following confirmed:


"It looks like you are not the only one who has problems with Target Display Mode in combination with MacBooks from 2017-2018. That is why I would like to inform you that Apple is aware of the problem and tries to solve it as soon as possible.


In the meantime, Apple asks its customers to exercise patience. As soon as the solution is available, Apple shares it with its customers via a software update."


Software update coming soon finally 🙂

Sep 10, 2018 11:10 AM in response to PENG ZHAO

It's this dock: https://www.macworld.com/article/2037026/review-belkins-thunderbolt-express-dock -lets-you-get-plugged-in-easily.html

The USB-C / TB3 to TB-Adapter works fine for connecting the 2018 MBP to the dock.

The trick seems to be daisy chaining the MBP and iMac through the dock (or through a Thunderbolt Harddrive, as another user reported) instead of connecting them directly.

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 12, 2018 1:15 PM in response to Pennock

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.

Sep 13, 2018 10:13 AM in response to researcher_ash

Reply to self.


With SMC reboots of both computers there's been no change.


Have been asked to take new MBP into a genius bar. No way. I kept mentioning this forum and that Apple engineers could easily replicate the issue the their labs. Taking a call back tomorrow and will report but likely no change.


With research I find that Thunderbolt 3 can only transform itself into Thunderbolt 2, VGA or HDMI. To get other signals from these MBP ports is to obviously use them as USB-C but USB signals can't support monitors (I don't think).


Question is: whether to sell the iMac and buy a new screen that takes HDMI? Maybe.

Sep 13, 2018 1:20 PM in response to researcher_ash

researcher_ash,


Most of us have gotten the run-around like you. However a few people here talked to engineers recently that said Apple is aware and working on a fix. Hopefully your callback tomorrow is from someone who is familiar with this issue and can clarify an answer.


HDMI does work with the new MBP's. My company bought two, and one is hooked up to an HDMI monitor and works fine. The other we needed to use Target Display Mode to an iMac which of course doesn't work. However you shouldn't have to buy a new monitor, Apple needs to fix this.

2018 MacBook Pro Target Display Mode Not Working

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.