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The March 2015 update of Apple's 13" MacBook Pro Retina Display, model A1502, features fifth-generation Intel Core i5 and i7 processors and introduces the Force Touch trackpad.

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Z key not working, replaced everything and still fails. Help.

So, full description of the problem first: When any disk in any mode is booted up on my MBP, the Z key doesn’t function. However, when it’s first turned on, when you first hit a key, it always types Z first, unless you hit the Z key first, then it just keeps typing Z like your holding it down until you hit another key. This effects my startup commands as well, so far all I can do is an SMC reset, go into single-user, and disk recovery, but that’s it.

So! Where it gets really weird is what I’ve tried so far. To date, I’ve:

  • Reset SMC and NVRAM (several times, NVRAM from single-user)
  • Swapped out multiple keyboards
  • Replaced the Trackpad cable (just in case)
  • Put in a new disk and installed a completely fresh copy of Mojave, then tried Mavericks for kicks, just in case.
  • Stuck another disk in that was installed with OSX from a completely different early 2015, one with a working Z key.
  • Checked and messed with pretty much every computer settings file that has to do with a keyboard

At this point I’m at a loss. There was no liquid damage on the device, and no other damage. I really don’t want to replace the mobo, and I’m down to solder or replace anything on that board to get this working, but if it was a trace that failed, I would assume at least that more than 1 key would be effected, since they are grouped, save for left bottom 3 and caps lock. I am officially out of ideas. Help.

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I understand you don’t like the idea, but after all that parts replacing and software resetting, I’m afraid there’s nothing left except a logic board side failure. The IC taking care of keyboard inputs seems to be your first and only candidate for replacement to fix the issue.

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You can replace the logic board with the guide below. There are links to buy a new board in the "parts" section of the guide.

MacBook Pro 13" Retina Display Early 2015 Logic Board Replacement

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Ya know, I'm down to replace the keyboard controller, but I can't find the schematics to save my life. Any advice?

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@reverend_bishop I can't help with that, but if you google for 820-3476 boardview/schematics I'm pretty sure you may find some useful hints ;)

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@arbaman Thank you again for your help, I've finally found the culprit, however I think I've hit a brick wall. Turns out it is one of the I/O expanders that's faulty, but the part doesn't seem to be sold pretty much anywhere, and I don't have any junk boards lying around with the same chip. Thanks again for pointing me in the right direction though! I have learned so much :D

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@reverend_bishop What do you mean exactly by I/O expander ? I can't figure out what that is and how it interacts with keyboard. Boards for spares can be found on ebay, there are a couple chinese sellers removing main chips and selling the rest quite cheap. Just make sure the board has the part you'll need with a direct enquiry before buying.

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Pop the cap off the Z key and see what sticky stuff is holding the key depressed and clean it off. Wet your cleaning cloth lightly first. Never spay any cleaner directly onto your machine.

Next, try resetting the PMU/SMC. Shut down your MBP, plug in the power cord, hold down on the left hand side of the keyboard, shift, control, option and the power key all together. Hold 'em down for about 50 seconds, then release 'em, and then press the power key...also holding down Apple, Option P and R keys for 3 chimes as the MPB is booting up may help you.... check to see what country your keyboard is set to --which should be at the top of the screen...looks like it could be Czech or Polish or Serbian....,.

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@mayer I think you missed something sir... the OP has already done this "Reset SMC and NVRAM (several times, NVRAM from single-user)".

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@ajcooke01 I wasn't there so I don't know if was done correctly if the Z key was also being depressed.

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@mayer true, that is a possibility.

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Well, the OP swapped out multiple keyboards too :)

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There have been suggestion that this could be a virus. Best to boot from an external drive and run a goo (Paid For) Anti-virus that the refs are current on to find out. I like Symantec Endpoint Protection.

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