Q: sd card on iMac not working with el capitan

You may find your journey wasted if on finding the sd card is recognised you do not wait until the laptop or computer hours to sleep as this appears to be where the issue is. By this I mean that once you device goes to sleep, on awakening it won't remember the sd card and you will have to reboot the device. As I have posted previously, if you want to be able to access your ad card over several hrs but you may have to leave the pc or lap top to do something else then go into settings, then power saving and set all settings to never. This I have found to always work. I am surprised that he apple support team are not advising people to use this method as all other methods work until the computer goes to sleep again. So try my method first as you may just save a wasted trip. Failing that you may wish to wait for the next version of IOS ammusing called LSD. Get it!

All this is lovely IF your Mac sees the SD at all. Mine doesn't. 

Thanks for your response.  I had read all the earlier threads about the resets (I've done them as well - no luck).  Both of my computers have long been set to "never sleep" due to support they provide to various equipment and other external drives on my home network.  I also have an older iMac (2008) and a 2011 Macbook pro, 2 iPads, 4 apple tv's, iPhones - etc, so I'm pretty familiar with osx/ios updates. I have never had to contact Apple about any OS X install since 2008 until El Capitan.  Some are nagging issues that are slowly improving.  Others, I'm still attempting to work through - including - the SD card reader issue.

Signed -

Frustrated.  This is not fun or a good use of my time.

I am interested to know if the sd card works if:

a: used via a camera's usb lead

b: used via a sd card reader

c: used via a printers usb slot

d: if the card was formatted in the mark and then tried to see if it could be read......obviously you must save via whatever means you can before doing this other wise you will lose the contents.

e: what has apple said to you about this problem

Can you tell me what response you have got from apple regarding this issue?

Yes, the card works everywhere but my Macbook's reader. And I had a USB 3.0 hub that worked BEFORE the El Cap update.

I've informed Apple (Via Developer Bug Report...maybe I'm not supposed to mention that, but they had better NOT get upset...)about this back in an early El Cap beta and they first had me do a clean install...no luck. Then they said make a new partition and reinstall Mavericks...I'm not going to do that.  I sent them last week the link I provided above, and they said thanks for the update. I followed with, "NOW FIX THE DARN THING!!!"  No response to that as yet.

I solved the problem with SD cards on my iMac late 2009 in this way: in recovery mode I launched the terminal and typed csrutil disable. Then I rebooted and went to System / Library / Extensions and deleted the file AppleStorageDrivers.kext. After restarting, the result is that, despite the System report tells me the computer doesn't contain any card reader, my SD card appears on my screen and it works perfectly, though with a different icon. I don't know what to say, I'm still testing but so far the card has not been expelled. Obviously I did this at my own risk, but if there were problems, with an application like Pacifist is easy to reinstall the deleted file.

This would support the information I posted earlier, indicating that this is a SOFTWARE problem!!!!

And naturally it didn't work on my computer  

Thats good news for you. Let us all know i you go ver the next week and i will try the same trick on my Mac

Yes I'll let you know. At the time after a night in the sleep mode everything it is still functioning. Here is what the system profile says. If it works for someone else, please let me know, it's simple and harmless

Everyone...

It appears, to be tested more, and more again, that OS X El Capitan update 10.11.4 may have addressed this problem.

I updated less than an hour ago and my testing is limited, but I have used an SDHC card, put the computer to sleep, and used an SDHC card again and it worked. I'll be testing this more over the next few days, but Apple (four updates later mind you) may have addressed the SDHC card reader issue. If true, I will take back all the nasty things I've said, Well, most of them. Some? Aw, all of them.

A big (conditional until proved) thank you.

As an aside, after the installation restart, my USB Apple keyboard and mouse were not recognized and I had to break out the Bluetooth stuff to login. This is another El Capitan issue. Flaky USB. I had to move the USB connector from one port to another to get connected. Many posts on this issue too. Next time?

On a positive note, my problem with Calendar spinning the color wheel for like ten seconds between typed characters when adding/creating an event is improved. Still some color wheel spinning, but  not like before. Calendar is useable again. Hope it stays this way. I tried all the suggestions on this too.

So, conditional hats off to the OS X team!

I hope others chime in with similar results and the problem stays away.

Cheers.

No joy here...

I'm really sorry, and angry too, it doesn't work! I installed the update this morning, and for a moment I hoped that this time the problem was finally solved. Unfortunately I was deceived, it worked for a while but eventually went back as usual: card ejected, reader disappeared. I think I'll go back to test the method I explained two days ago. At least it worked for two days!

Sorry to hear that the the update is not working for everyone.

On day 2, my iMac still accepts and mounts my SDHC cards after waking from extended sleep (2x). Hope it continues to behave.

This was always a sleep issue, I think. All the PRAM and other nonsense was a side show. That leaves me to wonder if the problem is unique to laptops, or certain hardware that has not been addressed.

Curious to hear from those for whom the updated worked as well as those for whom it failed.

Since the success on my iMac, I've updated my Mac Mini, but I haven't tested it for the fix. Will over time and soon.

SK!