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I have a 2009 IMac, which came with Mountain Lion. I've upgraded to 10.9.latest (Mavericks). Now, my imac has started freezing up all the time - I've tried reinstalling from the recovery partition but even that hangs, so I think I've got a hardware fault. How can I run the hardware test though?

I've tried holding D down - that just gives me the standard recovery mode options (restore from time machine, disk utility etc). I've tried inserting the original Mountain lion dvd and booting it - no options there either. I don't have the physical media for mavericks, just the DVD for mountain lion.

Update: I also have a snow leopard DVD, which doesn't seem to offer me any more options !

Can anyone shed some light?

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    Could you clarify a couple of things? If you are using a bluetooth keyboard, that can make it hard to trigger diagnostics so using/confirming you have a USB keyboard makes is more likely you can trigger alternate boot. Also, you say you have Mountain Lion DVD and then you say you don't have physical media. If you could explain that / resolve the conflict there, we might be able to assist better. – bmike Apr 21 '14 at 16:39
  • Hi. Sorry for the confusion, will edit post, but to summarize: Usb keyboard, and I have ML DVD, but no physical media for mavericks, – Matt Roberts Apr 21 '14 at 17:26
  • OK - somehow my brain was commingling Mavericks and Mountian Lion. The good news is hardware test is unbundled from OS and the bad news is sometimes when hardware failure strikes, the inability to run a test suite helps explain what part of the system is failing. – bmike Apr 21 '14 at 18:24
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Since it does not show up with D at start up lets look for it on your hard drive.

The AHT is stuffed into an AHTxx.dmg file and found on the Recovery HD volume that is also hidden.

First you have to make the hidden partitions visible

To enable the see all partitions in Disk Utility (the Debug Menu)

defaults write com.apple.DiskUtility DUDebugMenuEnabled 1

In Disk utility now there will be a tab called Debug.

Use it to show hidden partition.

You will now see the Hidden partition called Recovery and EFI.

Mount the Recovery to see the files in finder and find the AHTxx.dmg

If it is not there, try using internet recovery with cmd-r.

see this for more options.

Also, you might be able to download a copy of AHT using this link and providing the correct 4 digit model number. (upekkha on Github provides a handy list of mac models with the accompanying download link and more info.)

Apple does not publish that list since it is kind off back door to they service.

Here are few of them

2579 for Mac-F4218FC8 iMac6,1

2535 for Mac-F4218EC8 iMac5,2

2534 for Mac-F4228EC8 iMac5,1

2533 for Mac-F42786A9 iMac5,1

  • Thanks for all the help. Unfourtunately, I don't have an OS at the mo - one the things I tried was a fresh reinstall of osx which failed :( I was able to check the recovery partition though from terminal in the "recovery partition", and I can't see any .dmg files in there at all (not many files there at all, was showing all with ls -ah) – Matt Roberts Apr 21 '14 at 17:58
  • Also, CMD-R does nothing for me either - just boots the DVD if there is one, else starts the recovery partition. – Matt Roberts Apr 21 '14 at 17:58
  • Reading you again it sounds like you keyboard is messed up, the D should not bring the recovery options, and the cmd-r should? – Ruskes Apr 21 '14 at 18:26
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For my 2011 iMac, only option-d invoked AHT. Just the d key (without the option key) did not work.

  • Same for Macbook Pro mid 2010 13''. – Shoe May 29 '16 at 9:41
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Instructions for using AHT:

Mac NoteBook and Desktop computers shipping with OS X 10.7 or later have a partition on the hard drive or flash storage that contains AHT. To start AHT on these computers please follow these instructions:

  1. Press the power button to turn on your computer.
  2. Press and hold the D key before the gray startup screen appears.
  3. It takes a minute or so for AHT to start up and inspect your hardware configuration. While this is taking place, an icon appears on the screen: aht
  4. When the process is complete, select your language and click the right arrow. If you aren't using a mouse, you can use the up and down arrows to select a language and then press the Return key.
  5. The AHT console appears. You can choose which sort of test or tests to perform:
    • To perform all of the basic tests, click the Test button or press the "T" key or the Return key.
    • To perform a more thorough diagnostic test, select the "Perform extended testing" checkbox under the Test button before you click the Test button.

Note: Your test results will appear in the window in the bottom-right of the console.

To exit AHT, click Restart or Shut Down at the bottom of the window.

Some Macintosh computers that shipped with OS X Lion and later support the use of Apple Hardware Test over the Internet. These computers will start up to an Internet-based version of AHT if the hard drive does not contain AHT. An Internet-enabled connection via Ethernet or Wi-Fi is required to use this feature. Internet-based AHT functions the same as AHT on the hard drive or flash storage outlined above.

The Mac NoteBook and Desktop computers listed in Computers that can be upgraded to use OS X Internet Recovery will require a firmware in order to support the Internet version of AHT. Without this update you may see the behavior discussed in this article.

However, it looks like you are doing the correct steps. If you aren't seeing the hardware test icon, then it might be that your AHT partition got removed somehow. Since you aren't seeing the "Apple Hardware Test does not support this machine" then it looks like the fix in that last paragraph won't work.

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