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Target Display Mode not working - MBP>iMac via Thunderbolt

I have a MBP 15" 2011 model (w/ thunderbolt) trying to connect to an iMac 27" 2012 model (w/ thunderbolt) via a thunderbolt cable to use the iMac as an external display.


When I press Command+F2 - Nothing happens.


I've checked the keyboard and made sure I am pressing Command+F2 (it is not a mac keyboard)


There are no preferences for target display mode on the comp that I can find...?


Any help would be muchly appreciated!


Thanks,

Scott

iMac, Mac OS X (10.7.2)

Posted on Aug 16, 2012 10:40 PM

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Question marked as Best reply

Posted on Jul 21, 2017 4:48 PM

I know it has been several years since this thread was active, but I thought I would post my solution for anyone that is still looking for a possible solution.


First off, let me say that I have been dealing with the nicest woman in level-two tech support with Apple, as well as their engineering team (yes, it was escalated up that far). They have looked at disk images of my MacBook Pro 15-inch, mid 2015 with Retina display and my iMac 21.5-inch, late 2013.


Quite by accident I found the solution. I read on another site that the Thunderbolt and the Mini DisplayPort share the same port. So ... I was wondered if perhaps I was not plugging my Thunderbolt cable into the correct port. I unplugged it from one port and into the other (even though they both had a little Thunderbolt icon). Then my eye caught that the roundness of the cable was not matching the squareness of the port. So I unplugged the Thunderbolt cable and gave the end a good hard stare ... (whispering to myself) oh, my, god. For the last two months I have been plugging and unplugging my Thunderbolt cable in upside-down. Who knew that was even possible?!? I plugged it in the correct way, mashed down Command+F2 and the screen changed to my MacBook Pro (I almost cried).


So YES, I am an idiot. I can only hope someone else is an idiot like me and this helps them.


Take care and please enjoy this free laugh on me.

11 replies
Question marked as Best reply

Jul 21, 2017 4:48 PM in response to Scottiemac11

I know it has been several years since this thread was active, but I thought I would post my solution for anyone that is still looking for a possible solution.


First off, let me say that I have been dealing with the nicest woman in level-two tech support with Apple, as well as their engineering team (yes, it was escalated up that far). They have looked at disk images of my MacBook Pro 15-inch, mid 2015 with Retina display and my iMac 21.5-inch, late 2013.


Quite by accident I found the solution. I read on another site that the Thunderbolt and the Mini DisplayPort share the same port. So ... I was wondered if perhaps I was not plugging my Thunderbolt cable into the correct port. I unplugged it from one port and into the other (even though they both had a little Thunderbolt icon). Then my eye caught that the roundness of the cable was not matching the squareness of the port. So I unplugged the Thunderbolt cable and gave the end a good hard stare ... (whispering to myself) oh, my, god. For the last two months I have been plugging and unplugging my Thunderbolt cable in upside-down. Who knew that was even possible?!? I plugged it in the correct way, mashed down Command+F2 and the screen changed to my MacBook Pro (I almost cried).


So YES, I am an idiot. I can only hope someone else is an idiot like me and this helps them.


Take care and please enjoy this free laugh on me.

Jul 22, 2017 5:37 AM in response to JDH-1967

I've made plenty of mistakes like that too. Forgetting to do X or ask Y or just forgetting Z, and then spending hours trying to find a "solution". Just yesterday I discovered that my new little logitech bluetooth keyboard wasn't working because I had the little on-off switch on the side turned off - after 90 minutes of frustration, complaints to Logitech etc. 😕


I always try at some point to take a deep breath, relax a moment and tell myself to start again from the beginning and think carefully. Sometimes the best solution is to sleep on it and then try again from scratch the next day.

Aug 19, 2012 6:11 AM in response to Scottiemac11

First - From what I've read about this in the Mac forums, you need an aluminum Mac keyboard connected to your iMac. The knowledge base articles about TDM do not mention this but a number of users have. (I've found that most help advice which Apple provides assumes a "default" hardware and software setup.)


Second - This is from another thread (if both Macs have thunderbolt ports, substitute thunderbolt cable for MDP cable):


Connect a Mini DisplayPort cable to the ports on each computer.

Boot primary computer (MBA).

Boot target computer (iMac).

Press ⌘-F2 on the keyboard of the external display computer.


The boot order is important - boot the target computer first and Target Mode won't work. This isn't apparent from the documentation.


Hope this helps.

Aug 23, 2012 8:17 PM in response to Scottiemac11

It seems (as well from other forums) the only way is to use the default Apple keyboard for this to work because the function keys work differently on other keyboards! I was trying to use a non-Apple keyboard in my attempts.


The MDP cable substitution is interesting and I'll have to give that a go, I know MDP cable doesn't work by just pressing ⌘-F2 on the 2nd computer as is.

I'll try the boot process and see how that goes.


Thanks.


Scott

Mar 23, 2013 1:06 PM in response to Scottiemac11

I've just isolated another case where this happens.


  1. iMac Late 2012 27"
  2. MacBook Pro 13" Late 2011


Pressing Command+F2 on the aluminum keyboard of the iMac switches displays. The MacBook Pro sees the iMac as a second display, but the display is black. Changing resolution or brightness of the iMac display via the Displays System Preference has no effect.


My iMac is connected to a Sony home theater amp via a TOSLink optical cable ( the Apple sort with the "jack" connector on the iMac end). Switching with the optical cable plugged into the iMac will result in a black screen. Unplugging the optical cable and switching works as expected.


I'll submit this as a bug.

Aug 19, 2013 3:28 AM in response to Kenneth Cohen1

Same problem here - iMac 27 and MacBook Pro, both 2011, hooked up, target disk mode works, but display mode does not. Only I'm trying to go the other way than most - I want the MacBook to be the display for the iMac. The iMac's screen has gone caput and I need it's processing power to edit video - does Target Display Mode work this way round or is it only MBP using iMac as a display?


I've tried all fixes listed here nothing happens when pressing command - F2 on the MBP.


If I press command - F2 on the iMac both screens flash blue and nothing else happens (I am using a third computer with screen sharing on to see the iMac's screen, as the iMac's LCD is cactus)

Target Display Mode not working - MBP>iMac via Thunderbolt

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