OS X Mountain Lion: If a Thunderbolt device isn’t working

This article has been archived and is no longer updated by Apple.
If a Thunderbolt device isn’t working
  • Make sure all Thunderbolt devices are turned on and all cables are connected. If any Thunderbolt device requires a power cord, make sure it’s plugged in.
  • Make sure you connect Thunderbolt devices with Thunderbolt cables, and not Mini DisplayPort cables. A Thunderbolt cable has a Thunderbolt icon on the connector.
  • Make sure you installed any software that came with the device. Check the manufacturer’s website for the latest software.
  • If the device is in a chain of devices, each connected to another with only one connected directly to the Thunderbolt port on your Mac, make sure that all the devices other than the one connected directly to your Mac have their power cords. (And if the device connected directly to your Mac requires a power cord, it should have one, too.) If a Mini DisplayPort device is part of the chain, make sure it’s at the end and is connected with a Mini DisplayPort cable. If the Thunderbolt device still doesn’t work, try plugging the device directly into your computer.
  • Open System Information, and then click Thunderbolt. If the device appears but does not work, the problem might be with the device. Review the device’s documentation for further troubleshooting steps.
  • If the device still doesn’t work, try quitting and restarting any apps that use the device, or choose Apple menu > Restart.

If these suggestions don’t work, see the documentation that came with the device for troubleshooting tips, or contact the manufacturer for help.

Published Date: Sep 4, 2015