This article explains how to troubleshoot a USB port on a Windows or Mac computer. There are a number of reasons why a USB port may stop working properly; for example a driver problem, a hardware problem or a problem with the USB device itself. After examining the USB port of the computer directly, you can run a diagnostic using the "Device Manager" program on Windows or try to solve the problem by resetting the SMC system management controller (from English "System Management Controller") or by resetting NVRAM on Mac. NVRAM and PRAM are two special memory portions in which a part of the firmware and some hardware configuration settings of a Mac are stored. USB of your Mac.
Steps
Part 1 of 4: Examine the USB Ports
Step 1. Visually check the inside of the faulty USB port
If you suspect that the communication port under consideration is not working properly, check the inside for dust, dirt or other foreign elements that could compromise its functionality.
Step 2. Connect multiple electronic devices of different nature to the USB port that is not working
If you've noticed that a specific device doesn't work when plugged into the USB port under consideration, try using a different device to see if the problem is with the communication port or with the device itself. If the second tool you plugged into the USB port is working fine, then the problem is most likely related to the first device.
Step 3. Try connecting USB devices to one of the other ports on the computer
If your device doesn't work when you connect it to a specific USB port on your system, try using a different one. If you can, try using different computers as well. This way you will have a chance to isolate the cause of the problem. If the USB device has no problem when you connect it to different ports, it means that most likely the malfunction is with the USB port.
Step 4. Check if the hardware connection is secure
If you notice a malfunction when connecting a device to a specific USB port, try gently moving the USB connector left and right and up and down to see if the connection is as tight as it should be or is strangely loose. Use the behavior of other USB ports that are working properly as a reference. If the USB connector appears to be loose when inserted into the port, the electrical connection may be adversely affected.
Step 5. Restart your computer
If you have determined that the USB port is not working properly by following the diagnostic steps described in this part of the article, try restarting your computer. Restarting the operating system allows you to reset the settings of various hardware components on your computer, which could fix any problems that may be present.
Step 6. After the reboot is complete, try plugging a device back into the offending USB port to see if it is now working properly
If the device still does not work, perform a thorough check using the "Device Manager" program.
Part 2 of 4: Using the Windows Device Management Software
Step 1. Access the Windows "Start" menu by clicking on the icon
You will have access to the main menu of the operating system. By default, the "Start" button is located in the lower left corner of the desktop.
Step 2. Enter the search string devmgmt.msc
This will search the entire system for the Windows "Device Manager" program.
Step 3. Click on "Device Manager"
It features an icon depicting a stylized printer.
Step 4. Click on the computer name
It is normally displayed in the upper right of the "Device Manager" window pane. It will appear highlighted in blue.
Step 5. Click the "Scan for hardware changes" icon
It features a computer monitor and a magnifying glass and is located at the top of the "Device Manager" window. By placing the mouse pointer on the icon indicated, the message "Detect hardware changes" will be displayed. The operating system will scan all hardware components of the computer for malfunctions. With any luck it should detect the faulty USB port.
Step 6. Connect a device to the USB port under test
After scanning your computer for hardware configuration changes using the "Device Manager" program, plug a USB device into the problematic port to see if it is functional. If everything works correctly, your job is done. If the problem persists, you can try uninstalling the USB controller using the "Device Manager" dialog.
Step 7. Double-click the Universal Serial Bus Controllers item displayed in the "Device Manager" window pane
You may need to scroll down the list in order to perform this step. A list of all USB devices and drivers on your computer will be displayed.
Step 8. Select a USB controller with the right mouse button
The precise name of these devices varies from computer to computer, but focus on the keyword "controller" displayed as part of the name. Clicking on a USB controller with the right mouse button will bring up a context menu.
Step 9. Click on Uninstall device
It is one of the options listed within the context menu that appeared. The USB controller you have selected will be uninstalled from the system. Repeat this step for all other controllers in the "Universal Serial Bus controllers" section of the list.
Step 10. Restart your computer
After uninstalling the USB controller you selected, restart your computer. This will cause the Windows operating system to scan for hardware changes and automatically reinstall any USB controllers you have removed.
Step 11. After the reboot is complete, try plugging a device back into the offending USB port to see if it is now working properly
If the device is working properly, your work is done. If the problem persists, it means that it is most likely a hardware malfunction related to the USB port under consideration and that you will need to contact a repair service or an experienced technician.
Part 3 of 4: Reset the System Management Controller (SMC) on Mac
Step 1. Turn off your Mac
Click on the "Apple" menu icon in the upper left corner of the screen, then click on the "Shut down" option from the menu that appears.
Step 2. Reset the SMC
In this case, the procedure to follow varies according to the Mac model in use:
- MacBook, MacBook Pro and MacBook Air: Press and hold the key combination ⇧ Shift + Control + ⌥ Option + Power until the light on the power supply flashes or changes color.
- iMac, iMac Pro and Mac Mini: unplug the computer from the mains, press and hold the "Power" button for about 5 seconds, then reconnect the power cable to the system.
Step 3. Press the power button
At this point, the SMC reset is complete and the Mac will begin its normal startup phase.
Step 4. After the reboot is complete, after resetting the SMC of the Mac, try plugging a device back into the offending USB port to see if it now works
If the device is communicating correctly, your work is done. If the problem persists, try performing a NVRAM or PRAM memory reset.
Part 4 of 4: Reset NVRAM and PRAM memory on Mac
Step 1. Turn off your Mac
Click on the "Apple" menu icon in the upper left corner of the screen, then click on the "Shut down" option from the menu that appears.
Step 2. Press the "Power" button to restart your Mac
Step 3. Press and hold the ⌘ Command + ⌥ Option + P + R key combination immediately after turning your Mac back on
Press the indicated keys without releasing them as soon as your Mac starts booting and until you hear a beep and see the screen flash. At this point the Mac will boot normally.
Step 4. At the end of the reboot, after resetting the NVRAM or PRAM memory of the Mac, try to reconnect a device to the offending USB port to check if it now works
If the device is communicating correctly, your work is done. If the problem persists, it most likely is a hardware problem related to the USB port under consideration and that you will need to contact a repair service or an experienced technician.
