Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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Mac keyboard and mouse pad unresponsive after Sierra update

I’m not entirely sure if this has been on another forum but I’ll be putting it here just in case.

I have a MBP mid 2012. It was running on Yosemite when I finally decided to upgrade it to Sierra but after my upgrade, the mouse pad and keyboard suddenly stopped working. The power key was working and the only time that the mouse pad and KB are working is when the MBP is on Internet Recovery.

What I did was I formatted it back to its stock OS which is Mavericks. I tested it for almost a week and the KB and mouse pad worked without any problem. So I tried to reinstall Sierra (thinking maybe the first install had an error) but the problem happened again.

External keyboard and mouse worked fine so I also tried the PRAM and SMC but it didn’t work either.

Put it back to Mavericks again but this time I tried upgrading it to High Sierra but the MBP worked so slow. SUPER slow and the screen was also flickering a bit.

I went to have it checked professionally (not in a Mac store since we don’t have a Mac Store near the area). They said that the cables for the mouse pad or the KB seemed to be fine. They tried what I did but to no avail. They also tried putting in their own hard drive but the problem is still there.

I want to attempt to upgrade it to Yosemite or El capitan but they’re no longer available on the AppStore and I don’t have a bootable USB.

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Update (05/11/2018)

Hey everyone, sorry I couldn’t get back to you sooner. I reverted my MBP to Yosemite and it seems to be working fine. Unfortunately I still can’t upgrade to Sierra or HS without the problems but for now it’s working this way. Thank you for the help though!

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@valelers, can you please confirm that you have the model with built-in DVD player, and that you do NOT have the Retina model?


@rany - Did I miss something here?? He listed the system as a 13" Unibody and made no mention of a retina system.


You didn’t miss anything @danj.

But how many times have you seen such an issue on Retina vs. a classical unibody?


Both could have encountered battery issues or have had a liquid spill.

In the case of the Uni, HDD SATA cable


@Rany I do have the DVD player.


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@valelers - If you replace the cable make sure you place some electricians tape on the uppercase where the cable rests to give it some additional protection. In addition, not overdo the folds as you don't want to damage the foil traces within it.

Here's the IFIXIT guide to replace the cable for reference: MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement and this is the part you'll need: MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable. I do strongly recommend you make a backup after you swap the cable out (TimeMachine) and then reformat the HDD as often I find the drive often has corruptions that need to be isolated due to the cable creating them.

MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable Image


MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable


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Kristine will be eternally grateful.
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