Target Display Not working on Mid2011 27 iMac

I have a mid 2011 iMac, and a 2015 mac book pro, whenever I press command+F2 I hear a ding rather than this target display mode. Cable is a new thunderbolt bought from apple. Anyone else had this problem?

iMac 27", macOS 10.13

Posted on Apr 18, 2019 5:02 AM

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Target display troubleshooting Hi All, I'm struggling here to figure out why target display mode is not working on my iMac and MacBook Pro. I've gone through the suggestions "If Command-F2 doesn't work" and no dice. Hoping maybe I just overlooked something or any suggestions you all have. Here's what I'm working with: iMac (21.5-inch, Mid 2010), MacOS Sierra 10.12.6 MacBook Pro (Retina, 15-inch, Mid 2015) MacOS High Sierra 10.13 Connecting the two via Mini DisplayPort to Mini DisplayPort cable(from amazon). Tried an Apple Thunderbolt cable I had laying around and it also doesn't work. Using Keyboard Viewer I confirmed Cmd. F2 is being pressed. Also tried Cmd. fn. F2 for good measure. Restarted both machines and reset the NVRAM on the iMac. Tried pressing Cmd F2 while logged in and logged out of profiles. Not sure what else to try other than buying yet another cable but I would really love to get this up and running. Thanks in Advance!
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target display mode doesn't work My mac makes a sound and doesn't do anything when I press command-f2 even when the cable is connected.
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Target display not working I have a new iMac (Retina 5K, 27-inch, 2020) running Catalina 10.15.7. I also have an old iMac (27-inch, Mid 2011) running High Sierra 10.13.6. I want to use the old iMac as a second monitor. The 2 iMacs are connected with a Thunderbolt cable. When I press Command-F2 on the old keyboard, nothing happens. I tried restating both iMacs and unplugging and replugging the Thunderbolt cable. I also tried login out and pressing Command-F2. I am using the original keyboard on the old iMac. The Thunderbolt cable is from the Apple store. What is wrong? Why does nothing happen when I press Command-F2?
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1 reply

rkaufmann87

Level 10

148,516 points

Apr 18, 2019 6:03 AM in response to nuboston

Reset the NVRAM on both computers with all peripherals disconnected and then re-attempt Target Display Mode.

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Target Display Not working on Mid2011 27 iMac

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