Hi camp194,
Thank you for using the Apple Support Communities.
We understand that your external hard drive isn't showing up on a Mac and we're happy to help!
If a USB device doesn’t work with Mac, "make sure it’s connected to your computer correctly, is plugged into a power outlet if it has a power cord, and has any necessary software installed.
- Check the power, port, and cable connections: Make sure the USB device is turned on and its cables are properly connected. If your computer has more than one USB port
, switch the device’s cable to another port. If you still can’t use the device, contact the manufacturer for more information. - If you can use the device after switching ports, connect another device to the first port. If you can’t use this device, shut down the computer and unplug it from the power outlet. Wait about a minute, then plug it back into the power outlet and start up your computer.
- If you still can’t use a device with the port, your computer may need to be serviced. See Find how to service or repair your Mac.
- Check for missing software: Make sure you installed the latest software for your device. Visit the manufacturer’s website for any updates.
- Check the USB hub: 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: On your Mac, choose Apple menu
> About This Mac. In the overview that appears, click the System Report button. - In the window that appears, see if the USB device is listed below Hardware in the list on the left. If the device appears but does not work, review the device’s documentation for further troubleshooting steps.
- Reopen apps: Quit and reopen any apps that use the device.
- Restart your Mac: Choose Apple menu > Restart."
For additional information check out the Apple Support articles below.
About USB on Mac computers
Use external storage devices with Mac
Contact a third-party vendor
We hope this helps.
Take care.
