Get Apple Hardware Test Boot Mode Back on Some OS X Lion Macs
Mac OS X Lion has changed how several helpful troubleshooting tools function, one being the reset password tool, and another is how Apple Hardware Test (AHT) mode works. Gone is AHT’s independent boot mode in favor of an internet based version that is dependent on Lion’s Internet Recovery instead. If you always have access to the internet, this isn’t a big deal, but if you can’t get online that’s not particularly useful.
There’s a solution, for some Macs at least, and that is to copy the old Apple Hardware Test utility over to the OS X Lion boot drive, which enables you to boot up from AHT by holding down the “D” key as usual. The catch? You’ll need a pre-Lion Mac that came with the Mac OS X Installation and Application install disks, yes, the DVD, from 10.6 or otherwise. This obviously rules out some of the newest Macs like the 2011 MacBook Air and Mac Mini from restoring onboard AHT, but it will work to restore the functionality to Macs that did ship with OS X install and app restore disks.
From Apple Support, here are the loose compatibility guidelines:
Apple Hardware Test is included on the DVDs that are shipped with some Macintosh computers. If the copy on your hard drive becomes unavailable, use the DVDs to run Apple Hardware Test.
• For Intel-based Apple computers that shipped with Mac OS X v10.5.4 or earlier, Apple Hardware Test is located on the Mac OS X Install Disc 1 and should be included with your computer.
• For Apple computers that shipped with Mac OS X v10.5.5 to 10.6.7, Apple Hardware Test is located on the Applications Install Disc 2 and should be included with your computer.
• For some Apple computers that shipped with OS X Lion, if Apple Hardware Test cannot be found on the hard drive, an Internet-based version starts up instead.
“Loose” meaning this isn’t an officially sanctioned method of restoring the feature from Apple, but rather it’s a way to determine if your Mac will be able to use this. If your Mac meets the requirements, meaning it didn’t ship with Lion pre-installed, here’s what you’ll need to do:
- Insert the Mac OS X installation disk into the Mac
- When the disk is mounted, make note of the volumes name and use the following command to copy the AHT diagnostic tool over to OS X Lion:
- For example if the volume name is “Applications Install Disc” then the command would be:
sudo cp -R /Volumes/DISKNAME/System/Library/CoreServices/.diagnostics /System/Library/CoreServices
sudo cp -R /Volumes/Applications\ Install\ Disc\/System/Library/CoreServices/.diagnostics /System/Library/CoreServices
You’ll need to authenticate the copy since it pertains to your system folder, but after this is done you can then boot the Mac from Apple Hardware Test again – without internet recovery – by holding down “D” on boot.
Apple Hardware Test is a helpful set of diagnostic tools, and when combined with things like the command line based MemTest or the GUI tool Rember to test for defective RAM modules, are good techniques to narrow down if some Mac problems are software or hardware related.
Thanks to Eric for sending the AHT tip from MacWorlds Hints