If you encounter any difficulties with USB devices, they are generally easily resolved. Basically, there are four kinds of error messages or alerts the Mac OS may use for a USB issue. These include:
- Not Enough Power to Function
- Not Enough Power for All Functions
- The USB driver needs to be updated. Would you like to search for the update on the internet?
- No Driver Found
No error message at all - device simply stops functioning
The Mac OS will not generate an error message at all in some cases, for the same reasons as the "Not Enough Power to Function" message. In these cases it is often necessary to do both of the following actions:
- Plug devices that draw a high amount of power directly into the computer's USB port, or connect it to its power supply if it has one.
- Unplug and replug the chain of USB devices if a high-draw device was connected to it. Connecting a high-draw device can potentially make the computer "deaf" to the entire chain of devices.
Not Enough Power to Function
The Mac OS will generate a "Not Enough Power to Function" message if:
- A device tries to draw too much power from the USB bus.
- One or more devices plugged into a hub requires more power than is available.
- You have attached a self-powered device (like a printer or floppy drive) and forgot to plug it into an electrical outlet.
Solution
If you're using a self-powered device, make sure it is plugged into a working electrical outlet. If not, try connecting the device directly to your computer or to a port on a powered hub. If you're connecting the USB device to a powered hub, make sure the hub is plugged into a working electrical outlet.
Not Enough Power For All Functions
The Mac OS will generate a "Not Enough Power for All Functions" message if there is enough power to supply some but not all of the functions the device is designed to provide.
Solution
As above, you'll need to see if the USB device has its own power cord and, if it does, you'll need to plug it into a working electrical outlet. Also, try plugging the cable for the USB device directly into to your computer or to an available port on a powered hub. If you're connecting the USB device to a powered hub, make sure the hub is plugged into a working electrical outlet.
The USB driver needs to be updated. Would you like to search for the update on the internet?
The Mac OS will generate this error message if it detects an out-of-date driver.
Solution
You can elect to download the driver from the Internet if you have a connection.
No Driver Found
The Mac OS will generate a "No Driver Found" message if a driver for the USB device is not found.
If you see this message, you might have forgotten to install the device driver, or you may have incorrectly installed the device driver.
Solution
Reinstall the software driver that came with the product, check the Extensions Manager control panel to see if it is disabled, or download and install the driver from the product vendor's website.
Other USB FAQs can be found in the following documents:
Related documents
61237: "Mac OS X: How to Troubleshoot a USB Device That Isn't Working"
58033: "USB: Device Troubleshooting"