Target display mode not working

When Apple introduced its late-2009 iMac units, it was clear the big integrated display screen on these systems might not only be offered for the accompanying computer system, but equivalent to the features of Targain Disk mode for tough drives, the display can be used for one more Mac.

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While Tarobtain Disk Setting needs you to rebegin the mechanism right into a unique mode, the use of Tarobtain Display ssuggest switches the monitor to accept input from an external resource, rather than the running system, simply as if you had actually unplugged it for alternative supplies.

To carry out this, first inspect the version of your iMac to ensure it was made in late-2009 or later, and also then ssuggest press Command-F2 after connecting the units through a compatible cable. Keep in mind that on a lot of Macs, the F-tricks are assigned to a mechanism function by default, so you will either need to revert this in the Keyboard device choices, or hold the “Fn” crucial in enhancement to the Command essential prior to tapping F2.

When you push this hotessential, the mechanism will certainly reprimary running, but the display will certainly now be easily accessible via the Thunderbolt link of the iMac, smaller devices such as laptops to manipulate the bigger display with the usage of a Thunderbolt cable.


1. iMac not switching to Target Display mode

If your iMac supports Tarobtain Display mode yet does not enter it, then try reestablishing your iMac’s SMC. In addition, for older iMac devices, be certain you are utilizing OS X 10.6.1 or later. In addition, be certain your have actually initially associated your iMac and secondary computer system before entering Taracquire Display mode.

Finally, be sure you have actually applied all software and also firmware updays for your iMac that Apple has actually made easily accessible. To execute this, go to the Apple food selection and select Software Update, and then install any kind of updates obtainable, especially those for SMC firmware or OS software program.

2. Encertain compatible connections


Thunderbolt relations deserve to be provided for displayport gadgets, yet not vice-versa.

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Even though Thunderbolt relations contain DisplayPort data, Taracquire Display mode on a Thunderbolt-equipped iMac not work with DisplayPort relations. Therefore, if you have actually a DisplayPort-equipped Mac and also wish to usage the mid-2011 (or later) iMac’s display screen as an external monitor, you will certainly not be able to.

For iMacs prior to the mid-2009 model, you will not have the ability to usage a Thunderbolt cable for the connection, so ensure you have actually a correct mini-displayport cable. Keep in mind that the Thunderbolt and Mini-Displayport connections look the very same, so differentiate these by the lightning-bolt symbol for Thunderbolt, vs the square bracketed symbol for Mini-Displayport.

3. Directly affix the iMac

While Thunderbolt supports daisy-chaining of tools, be sure to affix the iMac straight to the additional Mac

4. Media and also brightness controls

When in Target display screen mode, you should have the ability to adjust the iMac’s volume and also screen brightness; yet, save in mind these will certainly be readjusted from the iMac’s keyboard, and not from the one associated to the iMac.

5. Sound not playing via the iMac

If you have Target Display mode put up yet no audio is playing, then go to the Sound device preferences on your secondary Mac and encertain the iMac is schosen as the sound output device.

This entry was posted in Troubleshooting and tagged iMac, Mini DisplayPort, monitor, Taracquire Display, Thunderbolt on April 17, 2014 by Topher Kessler.

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37 thoughts on “Troubleshooting iMac Target Display mode”

Strod April 17, 2014 at 5:55 pm

Hi. Tip #3 argues you attach the iMac directly. I have actually two questions around that:

– Is that mandatory? I.e., does placing the iMac behind various other gadgets work sometimes, and also the pointer is supposed just as a troubleshooting step?

– If the iMac is linked straight, have the right to you daisy chain extra devices on its other Thunderbolt port?

Sphinn May 19, 2014 at 4:36 pm

Please confirm before I buy another cable: I think I now know why I can’t gain TDM to job-related via my setup based on the above article. Wanting to usage 21.5-inch Mid 2010 iMac (w/Mini Display Port) as an exterior monitor for a 27-inch Late 2012 iMac (w/Thunderbolt Port). I tried a Mini Display to Mini Display cable and it didn’t job-related. From your write-up, a Thunderbolt to Thunderbolt cable need to though, right? Only questioning bereason point #4 of this Apple post makes it look favor it still could not based on the older iMac (not being supported?). write-ups are great!

September 9, 2014 at 1:30 pm

I have actually a new MBPro Retina and also a late 2009 27 inch iMac. When I attach a miniDisplayPort cable in between them (as per Apple’s instructions) and press CMD F2, the iMac screen goes babsence for around 10 secs, then comes back on, however showing the iMac display not the MBPro. The reality that it goes babsence reflects the cable is functioning and also the command also is doing somepoint, however not what it have to. I usage an exterior display at job-related, so the output of the MBPro is working. All OS and firmware is approximately day (Mavericks on both). I have rebegan both and attempted this several times without success. Is tright here another possible incompatibility?

Martin Bonar December 10, 2014 at 9:35 pm

Same trouble. Then I opened System Preferences Displays and also found a brand-new option called ‘Arrangements.’ Checked the Mirror Display box and bingo! Set up is 2013 iMac 27 (Thunderbolt) to graphics crippled late 2009 iMac (MiniDisplayport) making use of MiniDisplayport to MiniDisplayport cable from MacLab.

Våghals October 25, 2014 at 6:28 am

My difficulty is that if I switch to TDM the sound out changes to internal speakers. I have a Roland sound card that is linked to my speakers and also prior to Yosemite it was no difficulty switching to TDM, the sound was still playing thru the sound card, however after upgrading to Yosemite it doesn’t occupational. After command also F2 it set sound out to internal speakers. How do I report this bug to Apple?

Dave January 27, 2015 at 1:56 pm

I have just purchased a late 2014 iMac retina display screen to hook up to my Macbook Pro retina (2012/13) I have actually a thunderbolt cable connected. Can i usage it as a dual monitor?

Brian March 4, 2015 at 3:43 am

Having trouble, hrs in, no solution, help thx!