Make sure the disk is listed in the left window.Attach the drive if it isn’t already connected.This should be done automatically when macOS detects the drive, but it doesn’t always work. If you think the drive works fine, let us see if we can manually attach it to macOS. By default, it doesn’t display much and the setting to not show external disks may be enabled. Use a USB power cable if you suspect this to be the issue.ĭepending on what you find here, you can troubleshoot either the drive or your Mac.įirst, make sure Finder will display drive icons. A USB cable carries 5V and if this is the sole power source for the drive, it may not be enough. Check that the drive is receiving enough power.Make sure your drive doesn’t have or use a power-saving or sleep function.Try attaching the external drive to another computer to see if it works on that one to rule out damage to the drive itself.Some imported drives come completely empty, and while macOS should detect and offer to format them, it doesn’t always work. Make sure the drive has been formatted.