Using Terminal to reset PRAM/NVRAM on an iMac with a T2 chip

[whitepowderma]

Hello everyone,

I have a 2020 27" iMac with the T2 chip running 11.1. I cannot reset the PRAM/NVRAM using the keyboard no matter what I try. I've read that you can reset it in Terminal. However, I'm concerned about doing it until I can confirm that these are the correct sudo commands. Can someone let me know if they are? Thanks.

 

[nambuccaheadsau]

Always a great idea to keep a wired kb and mouse on hand for installations etc. That looks correct, have a read of this on the subject:-

Resetting PRAM through Terminal

For some reason, my Mac won't let me reset my PRAM in the usual way (by holding the relevant keys down when restarting), simply nothing happens when I try it and my Mac just boots up normally every...

apple.stackexchange.com

 

[whitepowderma]

Always a great idea to keep a wired kb and mouse on hand for installations etc. That looks correct, have a read of this on the subject:-

Resetting PRAM through Terminal

For some reason, my Mac won't let me reset my PRAM in the usual way (by holding the relevant keys down when restarting), simply nothing happens when I try it and my Mac just boots up normally every...

apple.stackexchange.com

Thank you. I have a magic keyboard and I'm attaching the cable when trying to do the PRAM reset and I still cannot do it. I'm also removing all USB peripherals.

Edit: I tried it and received the following error:

nvram: Error clearing firmware variable fmm-mobileme-token-FMM: (iokit/common) not permitted

 

[chrfr]

Thank you. I have a magic keyboard and I'm attaching the cable when trying to do the PRAM reset and I still cannot do it. I'm also removing all USB peripherals.

Edit: I tried it and received the following error:

nvram: Error clearing firmware variable fmm-mobileme-token-FMM: (iokit/common) not permitted

Do you have a firmware password and/or is the computer signed in to Find My Mac?
If so, the NVRAM reset won't work with a firmware password, and FMM above refers to Find My Mac.

 

[whitepowderma]

That's strange for I don't have a firmware password. I'm going to have to see if I signed into Find My Mac, but I don't believe so. Maybe when I first purchased my computer during initial setup.

Mine may be working when I do it with the keyboard. Maybe it acts differently with the T2 chip? Either with or without the T2 chip, it should chime twice. The second chime is the reset. With my other iMac, a 2019 21.5" model, I hold the keys down upon startup. It chimes once and the Apple logo appears and disappears. It then chimes again louder about 5-7 seconds later and I let the keys go. It is then reset. However, with my 2020 T2 chip iMac, I hold the keys in upon startup. It chimes once and the Apple log appears and disappears. I then wait about 25 seconds and it chimes again. I then let the keys go. However, it is not a louder chime so I don't think it's resetting. Or maybe it is supposed to reset that way because of the T2 chip?