I know this is a reoccurring issue and I've gone through every forum, every topic and every blog post I could find. Two days ago my MacBook Pro 13 stopped detecting external monitors.
I'm using a Unitek HDMI to USB-C dongle which I know works fine. I've tested 3 different monitors, that have different resolutions and refresh rates, they all work fine.
I've got another 2019 MacBook Pro 13" that works fine with every single monitor; using the same cable/dongle combo.
What I've tried:
- plugged the dongle with and without charger also being plugged in,
- plugged the dongle when Mac was sleeping/off
- plugged in a USB-C -> USB-A dongle and connected a mouse to it – both ports work fine,
- restarted my Mac after I've plugged the USB-C cable in,
- reset NVRAM and SMC,
- reinstalled OS (with and without backup)
- tried clicking "Detect Displays" in Displays settings,
- closed the lid, plugged the cable in, opened the lid,
- installed DisplayLink drivers, uninstalled them.
When I connect the dongle, it's visible as BillBoard Device in the System Information -> USB (both Macs have that). I've also been watching and comparing Console logs when I connect/disconnect the monitor and here are some things that I've noticed:
- The Mac that works fine has some [Hot_Plug] events visible when I plug in the monitor,
- FB0 both have DisplayPort driver version 1.1, FB1 on working Mac has a version 1.2 (this information doesn't show up on non-working Mac)
The screen doesn't flicker when I connect any external display, there's no Arrangements tab visible. AirPlay works fine.
Both Macs are 2019 13" Pro with the same stuff inside – they both use Intel Iris 645 Graphics.
Any tips?
Best Answer
There's only one thing to do.... take it in for service.
The fact that it's being detected means your port is functioning. Now, you didn't specifically say so, but I'm assuming that the built-in display is working. Since you have the Intel Iris (Integrated) graphics, there's no failure with the graphics chipset (there's no discrete GPU)
However, there is a video mux (multiplexer) chip that "sends" video to the LCD, the external monitor, or both. This has likely died.
You've done a lot of diagnostics - actually gone a bit overboard with the re-installation of the OS. Safe Mode or Recovery Mode is sufficient for this. For the future, try this first and if you absolutely must have a clean install, do it to a USB flash drive (32GB is sufficient) so you're not wiping out your drive (and all your work) as a diagnostic procedure.