14 Replies Latest reply: Jan 29, 2010 2:37 PM by elmac
ActonBaby Level 1 Level 1 (0 points)
The USB ports on my Intel-iMac have ceased working, thus resulting in the keyboard and mouse not responding.

I have been getting the 'over-current' message on Start Up for a while now (even though the only things connected are a printer and the keyboard). The clock still works when I turn the iMac on, and the cursor arrow appears, but I have no way of controlling it.

I put the keyboard and mouse on another Mac, and they worked fine, so It's definitely the iMac USB ports.

Any ideas please?

iMac, Mac OS X (10.4.6)
  • rkaufmann87 Level 9 Level 9 (51,775 points)
    It's always helpful if you let us now what you've done to trouble shoot the problem before we post. However my first recommendation would be to do a SMC reset.


  • ActonBaby Level 1 Level 1 (0 points)
    Hello Roger

    All I've been able to do is turn my iMac off and on again as I have no other way of controlling it!

    The keyboard (and thus the mouse which is connected to a USB port on the keyboard), seem to have power for two seconds or so when it starts up, then nothing. The mouse also has no power (no red light underneath) when I plug it directly to one of the other iMac USB ports.

    Is it possible to perform an SMC reset without a working keyboard or mouse?
  • Bob Jackins Level 4 Level 4 (1,995 points)
  • ActonBaby Level 1 Level 1 (0 points)
    I've held down the power button for 10 seconds and then restarted, and also removed all cables for 15 seconds, reconnected them and restarted ... both sadly, without joy!

    When the iMac's been off a while and I start it up, the keyboard and mouse remain active for approximately 40 seconds before once again becoming unresponsive. But, as I mentioned, the iMac's clock continues to work, so the computer itself hasn't 'frozen' ...
  • rkaufmann87 Level 9 Level 9 (51,775 points)
    OK try doing a SMC and PRAM reset, follow these instructions to the letter:

    1. Turn off your iMac and unplug everything from it for 30 seconds.

    2. Plug in the power cord, keyboard and mouse only.

    3. Press the power button and immediately hold down the Option, Command, P & R keys until you hear the second gong then release the keys. Your machine will start up normally, then check for the issues you are having.
  • den.thed Level 7 Level 7 (25,375 points)
    Hi AB

    Thats good advice from those above, but if in fact the USB port protection has tripped then you might get it to reset by disconnecting the power for 3 to 5 minutes instead of 15 to 30 seconds.

    Also, try these steps: > http://support.apple.com/kb/HT1317

  • rkaufmann87 Level 9 Level 9 (51,775 points)
    I wasn't aware of that one, thanks Dennis.

  • ActonBaby Level 1 Level 1 (0 points)
    Good advice indeed ... but sadly ineffective in my case I'm afraid!

    After starting up, after about 30 seconds, my iMac presents me with three 'USB Over Current Notice', layered one over one another. There are three USB ports on the back of the iMac ... one for each port?
  • Macaby Level 3 Level 3 (910 points)
    Must be an older iMac as the new ones have 4 USB ports on the rear. I've had this problem before with non-Mac computers and was told that they are wired in series. So if one goes down, they all go down.

    Sounds to me this is a job for someone who is a take down artist. From previous computers, these USB ports connect directly to an internal board that probably will have to be replaced. I think if I were you, I would be thinking about getting an estimate for the repair cost and if it's too much, a new iMac.

    If your iMac supports BT, you might be able to get a BT keyboard.
  • den.thed Level 7 Level 7 (25,375 points)
    It does sound like maybe a bad keyboard, mouse or a shorted cord on one of them, but you also might have a bad USB port on the back of the iMac...

    Get a flashlight and your reading glasses and inspect all of the ports and cables for a bent or out of place prong.

    Then after getting the ports to reset and the iMac restarted, try connecting only the mouse to one of the ports on the back first and then the keyboard to see which one is causing the issue.

    If touching or plugging anything into the ports on the back causes a problem then there could be an internal short within the iMac.
  • sekigor Level 1 Level 1 (0 points)
    I download - IOUSBFamily Log Release for Mac OS X 10.6.2 (Fall 2009 Systems)(IOUSBFamily-390.4.4-log on my iMac from the Developer Member web site and after instaling my USB ports are not working.

    Can someboday please help me with this issue.

    Thank you in advance!
  • elmac Level 5 Level 5 (4,230 points)
    Hi, I would see if I could beg or borrow a BT k/b & mouse...L
  • Digdouglas Level 1 Level 1 (0 points)
    Wow. I have the same thing happening on an iMac 20" (Late 2008). Resetting the SMC changed nothing. I have tried all possible keyboard and mouse configurations, new keyboard and mouse, and even starting the machine with nothing plugged into the back of the machine, except the power (duh). The same "Over Current Notice" message pops up. This still happens when booting to an external drive.
  • elmac Level 5 Level 5 (4,230 points)
    Hi, I appreciate your concerns but hijacking another Post/Issue is best Not Done..

    In any event if your Mac's are under Applecare - an Apple Approved Service Agent or your nearest Apple store is the best advice I can offer...
    If you are completely out of warranty then an estimate from an Apple Approved Service Agent would be my advice..L