Unable to launch Apple Diagnostics

Hi everyone. I came across this thread and it seems relevant to my problems with my Late 2012 27" iMac not booting (and not letting me install, run diagnostics tests etc)...

Ok... I'll try and keep this concise:

Late 2012 3.4Ghz 8MB iMac worked great for years - started to get some random restarts last year - was running High Sierra

Tried an update to Mojave - failed - and iMac no-longer would boot / kept power re-cycling

Took it in for repair at good authorized Apple repair center. They managed to get all data off the Fusion drive (128GB original SSD/NVME + 1TB HDD). They tried reinstalling OS (I think they put original Snow Leopard on there). But kept getting re-boots.

Told me it was likely a Logic Board fault which would cost $800 or I could leave with them for recycling...

I decided I wanted to try and save the machine - I had read that the PSU boards on late 2012 iMacs often caused this sort of problem - so I brought the iMac home - learned how to open it up (iFixit) - bought a refurbished different PSU board for $100 and fitted it.

Did a quick test - and it booted ! hurrah.

At this point I thought I would give the machine a bit of boost so bought a 1TB SSD (Samsung EVO 860) and swapped out the HDD for the SSD. I expected this to kill the fusion drive setup - and it did - but I was ready to install Mojave from external USB disk I had made

This didn't seem to work - but when I tried Recovery mode from Internet, It remade fusion drive, installed High Sierra - and booted! So was super happy, re-sealed screen to machine and had a working iMac again.

So then... I tried installing Mojave again (10.14.4)... seemed ok to begin with then crash... then didn't boot

wouldn't even get to disk utilities or Terminal with my Mojave USB install disk

So I thought maybe the fusion disk setup was the culprit - and therefore if I could reset that - maybe unfuse the drives and install OS X to NVME and use the 1TB for applications and user data...

I bought a firewire cable (and a new Mac book Air....) and used Target Disc Mode - I could see drives - I ran first aid on them - no errors. I tried lots of different boot options - in the end I erased them both to try and get rid of fusion setup (pic is before erase).

Everything I did hasn't helped getting past a stuck progress bar on the Apple Logo.

I can't do internet recovery, USB recovering, Paragon Hard Disk Manager USB Key, Apple diagnostics (via internet) - I get same error about Can't load EFI...

So then I thought if its nothing to do with my internal drives (which should be blank) - maybe its my memory... so I tried removing one 4GB bank - same results. tried other... same results...

The only thing I can get into is Single User Mode - but not sure what to do there to help....

Before I start believing it is a logic board problem I really want to rule out some kind of SW/Firmware issue - or test HW somehow and check it works - but remember - I have NO OS installed at the moment

Any advice really appreciated.

Thanks

Can't run diagnostics

from the earlier posts I thought going back from 10.14.4 was not helping? If I want to try 10.13.6 how should I make such a USB installer please?

BTW - things are getting worse - now I can't even see the drives in Target Disk Mode :( - the host is showing Firewire symbol - but no driver appearing on my iMac (which I just upgraded to 10.14.5 - hope that hasn't caused that). If I use Single User Mode (with as USB 10.14.4 key in) I see the drives are there - but I don't seem to be able to run fsck on them (only the USB 'root')

What do I need to to in Single User Mode to be able to a) check other drives, b) see them in Target Disk Mode please?

Hello,

If you have:

An Apple Hardware Test CD:Start up from it as you would any other bootable disc:

Then:

1.Insert the Apple Hardware Test disc that came with your Mac into your Mac's optical drive.2.Restart your Mac by either:

• Selecting Restart in the Apple menu.
• Pressing the Command-Control-Eject keyboard shortcut.

3.Immediately press and hold the C key on your keyboard.4.Release the C key after the Apple Hardware Test appears on your display and indicates that it is loading

http://www.thexlab.com/faqs/aht.html

Can't do this without optical built-in drive... Maybe find a external optical reader... Would such an old CD still work?

I'd have thought if the internet AHT isn't working then nothing will?

Anyone have any luck downgrading the Boot ROM version?

Thanks for the continued and detailed effort.

As I can't get past UI Process start I can't get to utilities or terminal or reinstall - the only thing I can do is use Single User Mode - what I would *LOVE* is a way to install the latest known good EFI room to my Late 2012 (13,2) iMac from Single User Mode. The download for this exists on archived Apple Support site.

Anyone know whether this is possible please? Note I also would like to erase my internal SSD drives so I can at least see them from Target Disk Mode again - any hints and tips on that?

Tried FDISK but didn't seem to do much. And can't run full dskutil from Single User Mode...

Thanks

I experienced the same problem with my mid-2012 15" MacBook Pro running Mojave 10.14.5 and Boot ROM Version 226.0.0.0. Trying to launch diagnostics by holding down D or option-D give me

Error: 0x8000000000000003, Cannot Load 'EFI/Drivers/TestSupport.efi'
Status: 0x00000003

I have not found a solution yet.

I think this is a special Apple and authorized service center version. At the beginning there is a dialog box "do you have the customers permission"... to run... these diagnostic tests?"

They ran this from their local Ethernet...

Annoying that theirs works and ours (or even the network based consumer ADT doesn't!)

Yep - lots of good info from HandyMac

Well I'm about to buy a used (100% fully functional) logic board on eBay for $240.

It was that or I could order at BTO replacement iMac for $2800

Or I could pop down to the local apple store and drop $5K for entry level iMac Pro....

Just a note, you can get a Refurbed Mac from these good people & even can get a 2 Year Warranty, here's 2012s like yours is?

https://www.macofalltrades.com/shop/apple-desktops/?_bc_fsnf=1&Year=2012

The problem is that swapping out the logic board will probably fix the issue --- until you then load Mojave firmware which will then screw it up again...

You saw my screen shot earlier where their in house Diagnostics run ok (at least top level tests) whereas built in or Internet based don't...

Anyway... I got an old logic board which I will try and fit this well and I'll report back what happens.

Any Apple employee who sees this….

The photo is good evidence, but… it is highly unlikely that any Apple employee will see it, and even if someone does, it won't make any difference. Posting to this board is not equivalent to reporting a problem to Apple, nor to asking for a solution. You must either call Apple support about it (though the photo won't do any good because they can't see it over the phone), or – best if you can do it – put the photo on one of the computers that can't load the Diagnostics (actually Apple Hardware Test, I believe, on a 2012 model) and take it to an Apple Store to show them the problem, and ask for a solution. Otherwise, we can all discuss this forever but it'll make no impression on Apple. If we could come up with a solution among ourselves here, that would be fine, but we can't; Apple has to fix this.

I have this exact same error show up when I tried to run a diagnostic. Does you or anyone know what this means? Mind you I started having oi internet issues on my iMac (27 Inch, late 2012) with 2.9 GHz Intel Core i5 which caused me to run diagnostic test. Computer still works but want to know what this error means and if I should be concerned or take it to get repaired before it completely stops working. Any feedback would be greatly appreciated. Thanks in advance.

Yep. I agree with all your analysis. I work on embedded systems with UEFI bootloaders and we would certainly try and run tests from internal SoC memory before loading main OS to DDR etc.

So... Getting back to the big picture... I think we conclude that the Mojave or High Sierra latest installers that contain 283.0.0.0 EFI Firmware update (on late 2012 iMac ) load firmware that has got bugs in it that prevent apple hardware tests from running ?

But in my case it's worse - it also stops the machine from booting past UI Process start - suspecting a problem with GPU. The tech in the repair shop then pinned this on the logic board - ok but it was working before the firmware update... So is there not just a big that effects AHT running but maybe also some more aggressive clock or bus configuration setup in EFI boot that is more sensitive to an old maybe a little bit wonky GPU???

That's what is frustrating - I'm about to do a complicated HW swap out of logic board because of something which has been caused by a **** firmware update!!!

What do you think?

I agreed it was Apple's fault... just was hoping I could get AHT working - I didn't understand the earlier info that the right version of AHT wouldn't work with this Firmware - anyway - was quick test...

I'm still wondering though - I think there are two issues here... It seems my GPU is (now) not working - so a logic board swap could solve... then there is the firmware version and incompatibility with Apple Diagnostics... do we think EVERYONE with similar models ALL have this problem with latest firmware? That surely would be recognized by more people (including Apple)... ?

I see that the post recommending the GitHub article on AHTs has been promoted to "Helpful" – I don't by whom.

There is only one person that can award points associated with a solved or helpful on any of these forums - and that is the OP. Anyone can click the little helpful button, but unless there are many (don't recall the exact number), it won't result in any points.

And, it was not the post you mentioned, but this one:

I am unsubscribing from this thread.