I'm having an odd problem, I have a 2017 27" iMac, it comes with a bluetooth keyboard in the box. However, I swapped it out for a wired keyboard as I prefer Apple's older wired keyboards over the new bluetooth ones.

The issue is when the Mac boots the USB (wired) keyboard fails to work until it's booted into macOS. Anything like entering account passwords at the initial login screen or putting the Mac into recovery mode only works with the bluetooth keyboard, it acts as though the wired keyboard isn't even there.

The caps lock key doesn't even light up, it's like the USB bus isn't getting power until after macOS boots.

Is there a solution to this? Is there someway to set the USB keyboard to trusted or something?

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    +1 for a really interesting question.... Are you plugging the keyboard directly into the iMac or into a USB hub connected to the iMac? Oh...and welcome to Ask Different! – Allan Feb 18 '20 at 21:01
  • Have you tried disabling Bluetooth, then restarting? What happens then? – IconDaemon Feb 18 '20 at 21:11
  • @IconDaemon, that sounds terrifying. My account is password locked and my hard drive is encrypted, not sure what I would do if there was absolutely no input capability on boot. I'd be locked out. – Scott Lott Feb 18 '20 at 21:16
  • @Allan, no USB hub. Connected directly to the iMac. – Scott Lott Feb 18 '20 at 21:16
  • There's no T2 chip on this model iMac, so it's not that. The fact that it's happening pre-boot could indicate something to do with NVRAM. Try resetting the NVRAM by holding Cmd-Opt-P-R while booting. – Allan Feb 18 '20 at 21:22

I don't know why this is the case, but the USB keyboard does work on boot but only if it's in the second USB port on the back of the iMac. It's the second from the center of the mac, so the third from the outside. Every other USB port doesn't work before the Mac has booted up.

Confirmed with other USB devices as well, that port is the only functioning USB port before I boot into macOS.

It might be a hardware issue with this iMac, I don't have any other 2017 iMacs around me to test.

Thanks for the help guys!

  • Wow! I’m glad you found the solution! I’ve never experienced a USB port that was inactive prior to boot. On PCs and on Macs, I just plugged into the first port I had access to. +1 and starring as a favorite for future reference – Allan Feb 20 '20 at 4:45
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    Also, make sure to mark this as accepted. – Allan Feb 20 '20 at 4:46

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