USB Device Troubleshooting

The easiest way to check for software updates is to go to website of the company that your device is made by.

If your issue is with a single USB device that's not working, check the manufacturer's website to see if there's a driver or a driver update that you need to install.

Troubleshoot the device
If you've updated your software and checked the drivers but the issue still persists, try the following things:

1. Unplug the affected device from the USB port and then plug it back in. Make sure that the connection is secure. Note that USB plugs fit into ports one way only—if you try to plug them in upside-down, you won't have any success.
2. For troubleshooting purposes, unplug all USB accessories from the computer. Then start plugging in USB devices one at a time, testing each one to make sure they all work before adding the next. Sometimes two devices will conflict and won't work together. If you find this to be the case, contact the manufacturer for assistance.
3. Ask yourself, is this a new device that never worked, or is it a device that you've had for a while that suddenly stopped working? If it used to work, think about what changed just before the device stopped working. Did you recently add another new device? Install a new program? Try reverting the computer to the way it was before the device stopped working. If it works again, there is an incompatibility with the device and whatever you added. (See the section on troubleshooting device compatibility below.)
4. Open System Profiler from the Utilities folder, which is inside the Applications folder. From the Contents column on the left, under the Hardware header, select USB; the panel to the right will show all the USB devices that the computer recognizes. It may not identify them correctly by name, but it should have the right number of devices listed.
   • If the device shows up in System Profiler, even if the device doesn't work, the issue is usually due to software. Your best solution is to try updating the drivers, creating a new user, or reinstalling the system software.
   • If the device doesn't show up in System Profiler, the issue is more likely to be hardware—either the device or the USB port isn't working properly. In this event, continue on to the next item on this list. With each of the following items, check the System Profiler window (press Command-R to refresh the list) to see if the device appears.
5. If you have the device plugged into a USB hub or into your keyboard, plug it directly into one of the USB ports on the computer. If it works there, the issue is with the device to which it had been previously connected. The device may need more power than the port provides - see article about USB Hub Types for more information.
6. Check the device in all the USB ports on the computer. Also test each port using a good, working USB device. Sometimes one port on the computer will stop functioning, but others will still work. If this is the case, the computer may need to be serviced.
7. Does the affected device have a power cord? If it does, try unplugging and replugging it. Make sure it's plugged into a working power outlet (you can test the outlet by plugging in a lamp or clock).

Troubleshooting device compatibility
If you have several USB accessories plugged into your computer (such as a keyboard, mouse, hub, printer, scanner, camera, external drive), you may get an incompatibility between two of the devices. You can test to see if this is the case:

1. Unplug all USB accessories except for your Apple mouse and Apple keyboard.
2. Make sure the Apple mouse and Apple keyboard work as expected.
3. Reconnect one of your USB accessories to the computer. So, for example, you may now have your Apple mouse, Apple keyboard, and printer attached to the computer.
4. Make sure the accessories all work as expected. Move the mouse, type on the keyboard, and print a test page with the printer.
5. Continue with steps 3 and 4, gradually adding one accessory at a time, until something stops working as expected. At that point, you have pinpointed which device caused the issue - the most recent one you added. You may want to contact the manufacturer of that device to see if they have any suggestions or can offer you assistance.