Chosen Solution
Hello, Our iMac lost its’ HDD shortly after warranty had expired. We have never had Mac that didn’t croak so I always have a fresh boot disk that is created every other day. We have recently (about a year ago) had trouble where the external wouldn’t even boot. Booting into boot manager the only options were for an internet recovery. I was able to try all boot options and finally the external boot drive would after having unplugged everything and gradually plugging everything back in. Fast forward ahead a few months and the only way to restart is via boot manager (option key) but it was reliable. Fast forward ahead a bit more and not only did my external boot drive appear but also the internal HDD reappeared! I was even able to boot from it and back up the contents before it disappeared again. We are now in a state where boot manage works SOMETIMES but only if I unplug everything, start boot manager then add the external drive while boot manager. Oh and the internal HDD is back but the computer freezes I try to boot with it. Sorry for the belabored end of this question. Basically, it’s like the whole data bus just drops out of sight. I have tried USB, Thunderbolt connections and when having issues the computer sees no drives at all. I want to assume it is the logic board but how can I tell ultimately? Thank you so much.
Here is the answer folks… The croaked HDD that was still in the machine and connected was creating chaos on the data bus or so it appears. I disconnected it and SSD boot drive and the thing booted in 10 seconds. On my way to prepping new larger HDD to install in the machine. With Apple being Apple I’m expecting some boondoggle once I connect new spinning drive for it’s first boot. Check back in a couple of hours if interested.
What are the diagnostic LEDs telling you? iMac Intel 24" EMC 2134 and 2211 Diagnostic LED’s Here’s the LED’s placement and assignments
You may want to check your power cord, the power strip (better yet surge suppressor or still better UPS) as well as your outlet. Make sure your outlets ground connection is good and the blades polarity is correct using a outlet tester. You’ll also want to check the voltage at the outlet as well. I suspect your issue maybe related to your power/grounding service.
