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Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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SD card not detected after automatic update

So I've been refreshing old iMacs. This particular mid 2011 27” was working fine including the SD card, after installing HS I turned on auto updates and let it do its thing.

Previously the mac had Lion.

During the updates I got the one long solid beep which i believe is the boot rom EFI firmware being updated.

After that the mac restarted and now the SD card reader is not present under system profiler.

Looking at the SD card reader the led is blinking rapidly, I swapped it into another 2011 and the card reader works perfectly and gives a solid green led.

Tried 3 working SD card readers but all of them exhibit the same quick flashing led.

All the usual trouble shooting makes no difference, nvram, smc reset, battery replacement and full reformat including deletion of the EFI partition but alas nothing has resolved the issues.

I guess I will have to include a USB card reader in the sale of this imac which sucks as it already has 1 dead USB port.

If anyone has had this same fault and successfully fixed it I would like to know.


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Install SD card drivers.


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Seems to be a software issue in High Sierra that coincided with the auto update and boot rom update.

Before resorting to swapping U6100 bios chip I decided to try a internet recovery to Osx Lion, even though the installation failed, it was still on the installing bar some 12hrs later, after a forced reset and loading to my Snow leopard bootable USB, which BTW didn't work on this mid 2011 imac, the SD card is displayed in the list of disks and the SD card reader LED is now off.

I will try to reinstall HS again as hopefully this failed Lion install has solved the problem.

EDIT: High Sierra install with SD still working yes!!

Will go through the updates and hope survives.

EDIT 2: Happy to report after applying all the updates the card reader is still working.

Strange that the updates go in order of 2020-005, 2020-004, 2020-006? Guess its a apple thing…

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To start with the SD slot hardware is passive, only when you connect the SD card will it become active. What are the SD cards you are trying to read the systems slot is only able to read the older SDXC cards. Review your cards specs.

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I have another 10 working iMacs here they all list a built in SD card reader under hardware wether or not a SD card is present in the slot, the SD card I use to test works in all the 10 other iMacs and worked perfectly in the imac im trying to diagnose before the auto upgrade so Im sure the card is ok.

The SD card reader has a LED flashing constantly with or without a SD card inserted, the working imacs have a solids led when a card is inserted and no led when card is removed.

I can verify that several working SD card readers will not work in this imac but work fine in their respective machines..

I will probably replace the EFI boot rom chip and see if that fixes it.


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Jesse will be eternally grateful.
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