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One of the two USB ports of my Macbook Pro stop working frequently.

Once I reboot the computer, then two USB ports work well. But one of them (always the same one makes the problem) stops working. I don't know when exactly it occurs and why it occurs.

How can I fix this?

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I have experienced a similar issue with my MacBook Pro (early 2011), and I could narrow the cause down to a USB-powered harddrive. When I plug the drive in sometimes the USB port (usually the one closer to the display) stops working, I guess the drive, under some circumstances, is drawing too much power. Is this your case? The obvious solution is to use a USB hub (one that takes its power from an external power supply, of course). –  jaume Apr 3 '13 at 19:06
No, I only tried a cell phone charger and a mouse, neither worked while the other USB port works well with both devices. –  user67275 Apr 3 '13 at 19:29
I would wonder about hardware failure (perhaps heat-related?) –  Andrew Lazarus Apr 5 '13 at 5:41
Try running Apple Hardware test. –  Buscar웃 Apr 7 '13 at 18:11

2 Answers 2

The ports are designed to shut down when an over current situation is detected. It stands to reason that this circuit is reset at boot, so there could be damage to the sensor or damage / fault to the logic board or it could be a result of actual over current from whatever's connected.

Have you considered taking it in to a shop for a diagnosis?

Also, look in the Console app - all messages - and search for USB. You might be able to see the time when the over current (or other error condition is logged) since the system should notify the logging subsystem when a USB port gets shut down.

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A proper diagnostic will make it clear if it is the software or hardware problem. You should take it to your local Mac repair Store.

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