USB Accessories Disabled on iMac

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Level 1

6 points

USB Accessories Disabled on iMac

I keep getting the "USB Accessories Disabled" error on my iMac: "Unplug the accessory using too much power to re-enable USB devices".

I've unplugged all USB connections, and performed 3 SMC resets. However, this error message still keeps appearing, even with no USB devices plugged in. Sometimes I get the message repeated dozens of times. Any advice?

The machine is a 27-inch iMac, late 2013, running macOS High Sierra version 10.13.1, with a 3.2 GHz Intel Core i5.

iMac (27-inch, Late 2013), macOS High Sierra (10.13.1)

Posted on Nov 20, 2017 8:51 AM

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Answer 1

Best reply

den.thed

Level 9

77,176 points

Dec 11, 2017 12:25 AM in response to henners61

Do the SMC reset again, only this time disconnected from the power for 60 seconds instead of 15 seconds.

Then startup with a NVRAM reset, as per > How to reset NVRAM on your Mac - Apple Support

If that does not restore the USB ports, then you need to make a service appointment at your local Apple Store or Authorized Apple Service Provider. see > https://locate.apple.com/

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Answer 2

henners61 Author

Level 1

6 points

Dec 11, 2017 12:25 AM in response to ostatesman

I took my iMac to the Apple Store, and they did diagnose no USB power on two of the USB ports. It would cost £469 to have the logic board replaced, which is not really worth it.

I'm happy to live without USB power on two of the ports, but what is more difficult is the "USB Accessories Disabled" error message. This gets repeated dozens and dozens of times in High Sierra. When I wake my iMac out of sleep, the whole of the right hand side of the screen is filled-up with repeats of the same error message (and they continue stacking at the bottom of the screen) - I have to click on each one to dismiss it, and so spend a couple of minutes just repeatedly clicking the error messages to get rid of them, which is very annoying. I'm pretty sure this didn't happen in Sierra, only High Sierra.

Looking at the console, it looks like these messages are generated by the iOS Kernel. There does not appear to be any way for me to switch off these messages.

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Answer 3

zakp1

Level 1

4 points

Jan 13, 2018 10:38 AM in response to henners61

hey i've not long ago switched to samsung phone and accrued the issue stated above suddenly. As i was playing around with how to transfer files from samsung to macbook and started getting USB accessories Disabled

i tried all that and it didn't work... go to Disk Utility select the macintosh HD and and select on the top of the window First Aid, problem solved for me

hope it helps

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Answer 4

henners61 Author

Level 1

6 points

Nov 25, 2017 6:53 AM in response to den.thed

Thanks den.thed.

I've tried that, and am still getting the USB power error, so looks like I need to get a service appointment organised. Thanks for your help!

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Answer 5

Dec 10, 2017 6:59 AM in response to henners61

I am having the same issue with a late 2014 iMac and it didn't start until after I installed High Sierra (10.13.1). I think it might be a bug in HS.

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