2018 MacBook Pro Target Display Mode Not Working

researcher_ash wrote:

I had thought my iMac, the late-2009 27", was automatically going into TMD when a mini Display feed was stuck into it.

It is using Target Display Mode, but via Mini DisplayPort, not Thunderbolt (which wasn't on the 2009 iMac). The flicker problem is only with Thunderbolt using the 2018 MacPro,

Malcolm J. Rayfield wrote:

It is using Target Display Mode, but via Mini DisplayPort, not Thunderbolt (which wasn't on the 2009 iMac). The flicker problem is only with Thunderbolt using the 2018 MacPro,

But technically, should't it work? Isn't thunderbolt supossed to take a minidisplay cable?

I'm considering it as a cheaper solution to connect my MBP 2018 to my thunderbolt iMac mid 2011.

Opinions?

The iMac is not just a display, so a connection between the iMac and the MacBook will be created only when you would like. You just need to press command + F2 on iMac keyboard. Then, you will see that the iMac screen is flickering. If you have already done that, and still you see nothing, try to check that you did all right according to the “Targret Display Mode” apple page. Hope it helps.

ibpatol wrote:

Hi, how did you daisy chained them? I have a La Cie Thunderbolt-USB3 drive and I plugged it to the 2018 MBP using the USB 3 and to the iMac using the Thunderbolt port, but nothing happened, am I doing this wrong? Thanks

The drive should have one USB 3 port and two USB-C Thunderbolt 3 ports. Use only the USB-C Thunderbolt 3 ports, one to the MacBook Pro, one for iMsc in Target Display Mode.

Be sure to use Thunderbolt 3 compatible cables (lightning bolt icons on the plugs). Short (0.5 m) cables can handle both USB-C and Thunderbolt 3. Longer USB-C and Thunderbolt 3 cables are different.

Still a SMALL BUG with Target Display Mode (TDM).

I updated to the macOS Beta 10.14.1 and I was very happy it worked. But when I tried to screen share the iMac I was using as the TDM monitor I only get a black screen. In the past I would screen share the iMac so I could still see the desktop but for most my work use the faster laptop to do my work. Right now screen sharing just shows a black screen. I sent in a report through the apple bata software program, we will see what becomes of it. Is anyone else noticing this?

I think there are two problems here. One was that if it did connect, it was glitchy (in HighSierra or early Mojave Beta)

The latter is resolved based on Peng Zhao on Oct 8, 2018. However there are likely a number of people who have since upgraded to Mojave OS (full release) still experiencing this. Someone mentioned getting a hub solved their problem. The reason that solved the issue, is that a lot of us are probably using Apple's Thunderbolt 3 to Thunderbolt 2 adaptor, and it, unlike previous versions Thunderbolt adaptors, does not support MiniDisplayport which is what are on the early model iMacs. Per this article How to Connect Your 2016 MacBook Pro to a mini DisplayPort Monitor

I recommend finding a cheap adaptor on Amazon or Newegg https://www.newegg.com/Product/Product.aspx?Item=9SIA7255RK7908&ignorebbr=1&nm_m c=KNC-GoogleMKP-PC&cm_mmc=KNC-GoogleMKP-…

Hi all,

Ok great... Progress. Running 10.14.1 I can and am currently connected to my iMac in TDM. One thing though... It doesn't seem a guarantee. I mean this in the sense that once it's on, it's on but getting the iMac into TDM feels a bit hit and miss with no particular pattern. 9/10 the screen will go blank and then come back to the os running on the iMac as opposed to switching to external monitor mode. I switch the connection to MBP restart each machine a few times and eventually it works but it feels like it lacks science!

My working configurations run form different ports so it seems all 4 thunderbolt 3 ports work. I'm also Running an LG ultrafine 5K but even if I take this out of the equation the getting the iMac into TDM feels a bit "will it or won't it" each time.

Anyone else experienced this or have any ideas?

At least it is working once it gets going though!

Thanks!

Thanks for the great thread.

I *was* a happy 2015MBP 15" -> Apple TB2 cable -> Mid2011 27" iMac Target Display user.

Recently replaced with 2018 15"MBP (Vega20) -> TB3-2dongle-> Apple TB2 cable ->Mid2011 iMac Target Display:

...NO JOY

OS10.14.3

I have tried many solutions on this thread including pass through OWC T3 doc, tried 2x TB3-2dongles, every combo of port connection, updated iMac to its most recent OS, reset PMC on iMac.

In frustration I bought a LG5K, but would still like to get a solution for the iMac.

Has anyone got a mid-2011 iMac working with the latest 15"MBP?

Thanks, Aron

How have they fixed it? I have a new 2018 Mac Mini and a 2011 27 inch iMac. I am not able to update my OS to Mojave in the iMac and so it is only at High Sierra level (2011 is to old for Mojave). I have the connectors (Thunderbolt 2-3) recommended by the Apple Store. Target Display Mode does not work. This means I had to buy a monitor and the whole reason for buying the Mac Mini (to keep the old screen) has been lost. Still it would be nice for someone to let me know how I can use the iMac as a second screen, if Apple ever get to solve this problem.

You should not need Mojave on your iMac to use this feature.

Users complaints here were that the screen flickered and misbehaved on older versions, not that it did not work at all.

Getting the correct function-key keystrokes on your iMac to activate the feature is likely the sticking point.

After a week of trying all the suggestions from this thread and beyond, target display mode finally worked for my MBP 15" 2018 with a late 2013 iMac.

My initial setting was using a thunderbolt2- HDMI cable connected to a SATECHI dock, which in turn was connected via USB-c to my MBP.

It seems the dock wasn't powerful enough for a 15" MBP (only 60W and 15" requires 87W). So I instead I left the dock for everything else (iPhone, mouse, etc) and tried a single connection with a thunderbolt2-thunderbolt2 cable connected to a thunderbolt2-thunderbolt3 adaptor into the MBP. Worked instantly!! :)

Just a note: Cmd+Fn+F2 did it.

Good luck!

Same Problem on my side with MBP 2018. All works with my old MBP.
Using original Apple TB2 Adapter and cable.

Mini display adapter "UpTab". on Amazon or ePay. It is female thunderbolt to USBc and the only way I got my 24" CinemaView working.

Not true!! You can connect only from the bottom left C so no more two iMacs! The other 3 Cs do not respond.