Can't run Apple Diagnostics on 2011 iMac

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Can't run Apple Diagnostics on 2011 iMac

I have a 2011 iMac running 10.13.6. I just booted it up for first time in I think 5 years. It's acting a bit strange, most notably boot pauses for a very long time, graphics seem very slow, and some weird screen refresh patterns when the desktop is first brought up. Activity Monitor showed some initial activity after boot (virus scans and the like), but that has settled down and I still see these issues.

The first thing I tried was to boot in safe mode by holding down the shift key, but that didn't seem to help with any of the issues.

Next thing I tried was booting with option-V to see what was going on during the boot delays, but that did not result in the expected verbose boot logging to the screen.

I then tried option-R for recovery mode. That did work, but there is nothing really there to help me diagnose the problems.

I then tried booting while holding D to run Apple Diagnostics, but like option-V it did nothing. I also tried cmd-D and option-D.

One other thing to note is that the I am using File Vault. So after a reboot I'm almost immediately prompted to provide credentials to unlock the disk, and then go through a very long reboot before being prompted for credentials again, this time to login. The login process is pretty quick at that point.

My question here is mostly what is going on with the boot keys? Why are some of them not working? Is there anything else I should be trying? Is there any other way to run Apple Diagnostics?

Posted on Feb 28, 2025 11:57 PM

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Answer 1

Top-ranking reply

Allan Jones

Level 9

77,882 points

Mar 1, 2025 9:56 AM in response to cjp987

That was one of the last Macs to ship with optical system install/restore disks, and one had Apple Hardware Test, the predecessor to Apple Diagnostics. Do you have the disks?

How to use Apple Hardware Test on your Mac - Apple Support

Note the "disconnect" caution in Step 1. That could be the issue.

Per that article, the newer Apple Diagnostics worked on Macs introduced after June 2013.

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Answer 2

kaz-k

Level 9

51,084 points

Mar 1, 2025 3:42 AM in response to cjp987

Hi,

If Apple Hardware Test doesn't start and your computer was released in 2011 or later, reboot the computer and press ⌥ Option + D to start the hardware test over the internet. Select your network connection, enter the password (if needed), and press the checkmark

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Answer 3

cjp987 Author

Level 1

41 points

Mar 2, 2025 7:50 PM in response to Allan Jones

I finally figured it out. Even though the Application Installer DVD is not an OSX bootable disk, if you have it inserted when booting and hold the D key, it will boot into Apple Hardware Test.

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Answer 4

cjp987 Author

Level 1

41 points

Mar 1, 2025 12:07 PM in response to kaz-k

I have to make a correction to my initial post. Although I do have a mid 2011 iMac, it's actually a late 2009 iMac that is having this issue. I got the two machines mixed up. Holding the D key down when booting the mid 2011 iMac does actually work and runs Apple Hardware Test.

So for this 2009 iMac I believe I do have the original install disk. One is labeled "iMac Mac OS X Install DVD". It installs 10.6.2 and is dated 2009, so seems like the right disk. There is also an "IMac Applications Install DVD" that comes with it.

For the OS X Install DVD, it has issues. I did manage to boot into it once yesterday after a few failed attempts to get the iMac to mount it, but now it is back to not mounting it again. When I did get it to boot yesterday, there were no signs of AHT in the Utilities menu. I'm thinking now maybe I need to set it as the startup disk and hold down the D key while booting it, but at the moment the disk won't even mount. I'll see if I can get it working again.

For the Applications Install DVD, there is an installer package and an "Apple Hardware Test Read Me" file, which is actually an app. The file basically gives the same "hold the D key down" instructions. It says it that doesn't work then boot using a disk that has AHT, and goes on to say that the disk containing this file should have it, but it doesn't and is not a bootable DVD.

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Answer 5

Allan Jones

Level 9

77,882 points

Mar 2, 2025 11:02 AM in response to cjp987

For the OS X Install DVD, it has issues. I did manage to boot into it once yesterday after a few failed attempts to get the iMac to mount it, but now it is back to not mounting it again

That could be as simple as a dirty optical drive. Slot-load optical drives get filthy, especially when sitting unused. You can get a drive cleaning disk from most computer stores, home electronics shops, of even office supply stores. Most are US$5-10.

Dredging up old memories here, but I recall that if the computer shipped with more than one optical disk, the disk with AHT was so marked, but in a very small font small font size.

Can you post an image of the two optical disks? Use the "Image Insertion" icon in the text entry box's toolbar:

Posted images must be 5MB or less and in .png or .jpg format. Last time I tried, the "High Efficiency" format images from my iPhone would not post. On the phone, I went to Settings > Camera > Formats and changed the defalut to "Most compatible." Easier than having to convert the image with software.

AJ

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Answer 6

Allan Jones

Level 9

77,882 points

Mar 3, 2025 8:04 AM in response to cjp987

Excellent! Your follow-up post will help others.

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Can't run Apple Diagnostics on 2011 iMac

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