OS X Yosemite: If a USB device isn’t working

If a USB device isn’t working
If your USB device isn’t working, there are several things you can try to solve the problem

If a USB device isn’t working properly, make sure you connected it to your computer correctly, plugged it into a power outlet if it has a power cord, and installed any software it needs.

  • Check power and cables:
    Make sure the USB device is turned on and its cables are properly connected.
  • Check for missing software:
    Make sure you installed the latest software for your device. Visit the manufacturer’s website for any updates.
  • If the device is connected to a USB hub:
    Make sure the device and the hub are the same speed. Connect USB 3.0 SuperSpeed devices to a USB 3.0 SuperSpeed HUB, USB 2.0 Hi-Speed devices to a USB 2.0 Hi-Speed hub, and so on.
  • If the device doesn’t have a power cord and is plugged into another USB device that doesn’t have a power cord:
    Try plugging the device directly into your computer’s USB port or into a USB device that does have a power cord. You might need to disconnect and reconnect the other device as well, if it has stopped responding.
  • If you have many devices connected to your Mac:
    Disconnect all USB devices except the device you’re testing, an Apple keyboard, and an Apple mouse. Make sure that the device is connected directly to the computer, and that any hubs or extension cables are disconnected. If you can use the device now, the problem may be with one of the other USB devices or hubs you had connected to your computer. Try reconnecting them, one by one, to your computer. When you find the device causing the problem, review its documentation for further troubleshooting steps.
  • Verify that the device appears in System Information:
    Choose Apple menu > About This Mac. In the window that appears, click Overview, then click the System Report button to open System Information.

    In the window that appears, see if the USB device is listed below Hardware in the Contents list. If the device appears but does not work, review the device’s documentation for further troubleshooting steps.

  • Restart apps:
    Quit and restart any apps that use the device.
  • Restart your Mac:
    Choose Apple menu > Restart.
Last Modified: Sep 23, 2015
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