Home Forums Hardware Mac Desktops & Notebooks Apple Hardware Test stashed on new macs

I ran into something interesting today you may not be aware of, I wasn't.

I tried to start a macbook pro off a service diagnostic disc. Normally I put in the disc and hold "D" (for intels) to boot off the special discs I get from apple. They contain an advanced version of the hardware test and work on a number of machines instead of just one model.

Anyway, it booted to apple hardware test, for this model. (AHT 172 iirc) Turns out it's on the HARD DRIVE. (maybe) And holding "D" down prefers a diagnostic image on the hard drive over that in the optical drive.

Holding Option at boot was required to select the service diagnostic for testing. The hardware test does not show up in the startup picker, only the service diagnostic disc and the hard drive.

I've seen this once before on a new imac. Apparently apple is placing the hardware test image on a hidden partition on the hard drive somehow... possibly stuffing it in with the drivers? Or maybe the diagnostic image is in the ROM somewhere? (they're not very big, it COULD be made to fit I think)

Note: The AHT discs I've seen all tell you to hold down "A" to startup off the hardware test on the restore disk. I was holding "D", not "A", and normally those are not interchangeable.

Apple Hardware Test: iMac (Mid 2007) and later models ("The iMac (Mid 2007) and later model computers come with Apple Hardware Test installed on a separate hard drive partition. This partition is not visible in the Finder.")

Mac OS X 10.5 Leopard: Using Apple Hardware Test after erasing your disk ("If you're in this situation and need to use Apple Hardware Test, simply start from the DVD that came with your computer (not the Leopard installation disc) while holding the "D" key. Apple Hardware Test will run from the DVD.")

That's interesting. I am glad they also include it on the DVD, because otherwise erasing the hard drive (or replacing it) would remove the ability to run the hardware test.

This is a problem for some Windows computers, which ship with a "recovery partition" on the hard drive that you can use to reinstall Windows, but do not come with a set of Windows CDs. One of my sweeties had a cheap Dell that shipped this way, and her hard drive failed; replacing it was easy, but the replacement didn't have the "recovery partition," so Dell made her pony up $$ to get the recovery CDs so she could re-install Windows.

> I am glad they also include it on the DVD, because otherwise erasing the hard drive (or replacing it) would remove the ability to run the hardware test.

I believe I've read that AHT can be reinstalled as part of an erase and install.

Here we go... Quoted from "Apple Hardware Test: iMac (Mid 2007) and later models:"