Target display mode not wokring after upgrading to El Capitan

Question

Target display mode not wokring after upgrading to El Capitan

Hello,

I am using a mid-2015 MBP 15" with an mid-2011 iMac 21" as the secondary display using Target Display Mode.

When both were running Yosemite, TDM works fine but after I upgrade the MBP to El Capitan, activating TDM only results in the iMac showing a big bar across the screen with the screen gradually goes dark. Hitting CMD-F2 again the iMac returns normal.

First, I thought the iMac needs to be also in El Capitan, but after upgrading the iMac, the situation remains so.

Any help would be appreciated.

MacBook Pro (Retina, 15-inch, Mid 2015), OS X El Capitan (10.11)

Posted on Oct 5, 2015 7:30 AM

Reply

Answer 1

ndempsey

Level 1

4 points

Oct 19, 2015 11:39 AM in response to Griffin Cheng

I'm seeing this too. I cannot get a 2011 iMac running El Capitan to work in Target Display mode with a 2013 15 inch MacBook Pro running El Capitan.

Reply

Answer 2

OGELTHORPE

Level 9

57,305 points

Oct 19, 2015 1:39 PM in response to Griffin Cheng

Are the two Macs both using Thunderbolt ports?

https://support.apple.com/en-us/HT204592

Ciao.

Reply

Answer 3

ndempsey

Level 1

4 points

Oct 19, 2015 1:50 PM in response to OGELTHORPE

Both of the machines I'm trying have Thunderbolt ports, yes.

Reply

Answer 4

OGELTHORPE

Level 9

57,305 points

Oct 20, 2015 12:00 PM in response to ndempsey

If you have gone through all of the steps in the link I posted earlier, I have to assume that the Thunderbolt cable may be faulty or one of the two ports on the Macs. Test by connecting another Thunderbolt device or in worst case, make an appointment at an Apple store genius bar. The evaluation will be FREE.

Ciao.

Reply

Answer 5

Nov 5, 2015 11:14 PM in response to Griffin Cheng

I have exactly the same issue with my iMac 27 " (End 2013) and my MBA 13" (Mid 2012) - both on 10.11.1. It worked perfectly before the upgrade to El Capitan.

Reply

Answer 6

jmk-66

Level 1

0 points

Nov 9, 2015 9:43 AM in response to Griffin Cheng

I'm having the same problem with an iMac 27" (mid 2011) and a MacBook Pro 15" Retina (early 2013).

Everything was fine on Yosemite. Upgraded the iMac to El Capitan and Target Display Mode stopped working.

Switched out cables and ports, checked Keyboard prefs. No Fix.

Upgraded the MacBook Pro to El Capitan - still no fix.

Reply

Answer 7

Tenthrow

Level 1

8 points

Nov 30, 2015 11:57 AM in response to Griffin Cheng

You guys try a PRAM reset? Friend of mine had the same issues, reset PRAM on both machines and they are now working fine!

PRAM RESET

•Shut down the computer.

•Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.

•Turn on the computer.

•Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.

•Hold the keys down until the computer restarts and you hear the startup sound for the second time.

•Release the keys.

Reply

Answer 8

Dec 17, 2015 10:40 AM in response to Griffin Cheng

I have found that Target Display Mode will work, but only if I do command-f2 from the login screen. After logging in, the command does nothing.

I'm running a 2011 27-inch iMac as display with MacBook Air and a thunderbolt cable on El Capitan.

Hope this helps someone!

Reply

Answer 9

Mar 7, 2016 5:09 AM in response to Griffin Cheng

It's working fine with El Cap. I have a 2011 Macbook Pro connection to 2013 iMac. There are two modes - mirror and extended. Mirror does just that and extended allows you to use both displays simultaneously. Under System Pref<Displays click on the tab Arrangement. I was expecting the default to be Mirror and it's Extended. Also, upgrade both machines to latest El Cap and then reset SMC.

Reply

Answer 10

Jul 13, 2016 11:13 AM in response to Griffin Cheng

I was experiencing the same problem and turns out the solution for me was simple (yet silly) - my machine is apparently picky which end of the Thunderbolt cable is plugged into it. I simply swapped ends of the cable and BOOM! it worked. Had already tried resetting SMC & PRAM on both machines w/ no result. Simply turning the cable around resolved (Apple branded Thunderbolt cable, BTW).

Reply