2012 27" iMac Doesn't See Internal 1TB HDD

[SpecFoto]

Helping a friend out yesterday with his 2012 iMac 27", that has just a 1TB HDD, which the Mac now fails to see and won't starup from (White screen). I tried safe mode and mac OS recovery with no luck, so I zapped the pram and then used an external 1TB SSD with Mojave and hit option at startup and it did recognize it and start up off the external. About This Mac under the Storage tab did not show the internal drive, nor under the system report and the storage list there either, just my external. Apple Diagnostic won't start up with just the internal drive, saying it can't load the efs/test and gives an error code of 0x0000003. Disk Utility and DriveDX fail to see the internal drive as well, so I can't get any reports on its status. I brought the iMac home and ran it all night off my external SSD and the Mac works just fine otherswise and will reboot to the SSD, but still the internal HDD fails to show.

So it seems the internal 1TB HDD is dead, but before go to the trouble of taking it apart and replacing the HDD with a SSD is there anything else I should try? Could it be something else?

 

[nambuccaheadsau]

Yep your diagnosis is spot on.

 

[glenthompson]

In the event the drive is ok and the problem is something else like a cable, have a drive caddy available when you pull it to test it on another machine to see if the data is readable. However, based on your description, in the immortal words of Dr McCoy, “ It’s dead Jim”.

 

[SpecFoto]

Thanks guys for your confirmation. Already have the internal sensor and tape kit from OWC and ordered the 1TB SSD, which will be here in a few days. Is the internal sensor still needed for a SSD? In the meantime if anybody else wants to chime in, please do.