Random Keys Working Sporadically

I have a 2014 rMBP 15" machine. Yesterday afternoon the uiop, hjkl;, and bnm, keys became non responsive. I had just gotten back from vacation, so my first thought was that a liquid had found its way under the keys in that area. But a check with a loupe I saw no evidence for it. It really felt like it was a hardware problem and I was ready to set up an appointment at the local Dunce Bar. However, on a lark I decided to simply try booting into another user account. Voila'. All the keys worked. My first notion was to, on my main user account, move all of the Preference files (~/Library/Preferences/…) with a modification date around the time I first noticed the problem to the Desktop. There were about 30 of them. After doing this, I rebooted. The non-functional keys immediately became functional. The vast majority of the 30 Preference files I moved to the Desktop were immediately rebuilt by macOS. That left a half dozen or so Preference files from minor apps to ponder. I didn't bother. I deleted those, too. I had to re-enter serial numbers for a couple of apps as well.

This approach was only possible because I knew pretty much the exact time things went awry. However, the idea that the problem may involve only one user account might help. The idea that there is a corrupt User account preference file may help a little more. There is a bunch of these User Preference files that seem to churn all the time and which can be deleted with impunity.

You should be able to restart just fine even if you remove ALL of your User Preference files--or at least all the ones with Modification Dates ON or after your original keyboard problem. To prove one of them is at fault for keyboard woes, just remove (all of) the files in ~/Library/Preferences/ to a safe place and then restart. If you find that your keyboard problem is solved, then you can use the ancient and honored technique perfected by those of us who used to deal with corrupt preferences under System 6,7, 9 etc: Put half of your preference files back and restart. No problem? Assign those files a label or comment so you can keep track of them. Then add back half of the files you have not added back yet. Repeat until you get the problem. At that point you should have a small number of files to consider. You can then continue your winnowing process to find the individual file. As I said, I didn't bother. The files either regenerate themselves or can easily be regenerated when you set the prefs for the app that generates the preference.

So I thought I'd weigh in here to explain how these keyboards work:

This is the contactor array of a MacBook Pro 2011 13" . You're looking at it from back to front. Those round dots are where the silicone rubber "cones" cause the front array to make contact with the back array, telling the computer which key has been pushed. The width of these (I think deposited silver ) traces is about 0.5 mm.

Now you're only looking at the just the front array. You can see that the contact pads are connected in series. A break anywhere in the trace connecting them would cause the "downstream" keys to stop working.

So here you see a site where galvanic corrosion occurred. I know that this particular MBP was exposed to water. So I bought it very cheaply. I was able to clean and completely dry out the logic board and the MBP worked fine for a while but quickly the Q - W - E - R -T - Y - P keys got wonky then completely stopped working. I bought a replacement keyboard for cheap but then found out that it's held to the front frame with around 80 tiny screws. So I was using it with a BlueTooth keyboard. Recently I bit the bullet and for $69 bought an entire top case for my machine. Putting it in meant that the everything had to come out of and off the top case.

So you can see from the amount of corrosion, it doesn't take much to cause a failure. In this case a drop of liquid less than 0.5 mm would, over time with galvanic action, cause a failure. There was a post about someone who had their MBP in a leather case and when they opened it up there was a lot of moisture on it. It was winter where he lived and we figured it was condensation. So even without spills this could happen.

When I took this keyboard apart I was shocked to find how much crap was trapped under and inside the keyboard. Especially since I pride myself in never having any food/drink near my "precious!"

I, too, have a 4 year old Macbook Pro, and I am having the same problem. I have updated all my software and have done everything on the article allen a posted for troubleshooting my keyboard. Still having problems! This all started with my "D" button. Now it's my "L" and "K" buttons. Even typing this, I can't hit those buttons once and have the letter just pop up. I have to hit it repeatedly to get it to work. It's almost like there's a massive delay between when you hit the button and when the letter actually appears on the screen. When I opened my "Keyboard Viewer," sometimes it was showing my button highlighting when I hit it, and sometimes not at all. This is extremely frustrating! I really don't want to take my computer in, but I'm worried that's what I'm going to have to do if there isn't any other way to fix this.

I've had a similar problem for a while, too. Granted, it's a 2009 Mac Book Pro 17" Unibody, but it's not sustained any damage (dropping or liquid).

What's really, really strange is that 20 minutes ago, several keys on my homerow (I use the Dvorak layout) weren't working: i, d, h, t, n. Then, without restarting, without really doing anything, the keys started working fine. The first paragraph of this message was typed without any problems until I got to the letter "I" in liquid.

Now, I'm typing those letters with the on-screen keyboard or Dictation.

I'm really baffled about when it stops working, when it starts working, how long it lasts.

I have reinstalled the operating system, Mavericks, on an external disk and booted from that. I have installed no extra programs, copied no data - it's a clean, clean system. But, still the problems are intermittent.

Unfortunately, I'm living in Geneva Switzerland right now, and the Apple Store here is not very good.

Same issue for 13" MBA mid-2011 for all keys from Q to O (not P,.. yet), started yesterday. Very annoying since my password has some of them, and also reloading (Cmd+R) does not work. It starts working again if I press one of the keys for long time.

Edit: I have a "service battery" warning since a while so I guess it's time to fix it.

finally after months of research and not finding the answer here is the trouble shoot for you key problems.

just tap option key 5 times in your keyboard and your set to go.

hope it helps.

https://www.youtube.com/watch?v=wxSo1xnxL_k

Oh my god. Are you kidding me?? This sounded ridiculous, but at this point, I'll try anything.

So the option key didn't work, but you may have meant the ctrl key? Because I tapped it 5 times, and here I am typing on my macbook pro keyboard for the first time in over a week.

What. The. F.

I just started having the exact same issue as AndreiX this evening with my Mid 2012 MBP Retina. I discovered quite at random that if I press hard on the case on the speaker grilles to either side of the affected row (QWERTYUIOP), it starts working again. I think this lends credence to the theory that there's a loose connection somewhere under the keyboard.

Same issue here..... keys between E and O stopped working, I'm using now an external keyboard. Applying pressure on the sides of the laptpp or center of the keyboard makes the keyboard work again, so it is a wiring problem.

Since we all experience the same issue means this is a manufacturing problem.

I googled and seems a majority of people are experiencing this same issue.

We should evaluate starting a class action together with the same people experiencing mother board relate (graphic card) problems on the mbp 2011, probably there is a whole stock of mbp with defects in the manufacturing of their mother boards.

Consider that every user that writes here there are 100s with the same issue.

Best regards,

Water

Hi mathiascraig,

Is this the same machine you had the similar problem with last year?

This is a view of the keyboard contact array from the back looking at the front array. The back array is arranged mostly vertically.

I think my labeling is correct.

So as you can see the contacts here are all arranged and wired horizontally. Any crack in the trace will cause the downstream keys to stop working. (Not sure which way is downstream.)

"Sometimes I have been able to get them working again (like right now) by pressing hard on the case in the upper left of the top case."

That probably causes the fault/crack to mend itself temporarily.

"Sounds like replacing the keyboard may be the only answer?"

This has always worked for me. It's a bit of a pain because there are around 50 tiny screws that hold the keyboard to the front case. I always use a new keyboard off eBay. I've done 5 so far, twice on this machine (The first time I used a used keyboard which developed a repeating "ssss" problem after a month or so, which is why I use only new parts now.) which is exactly the one your have: 13", Early 2011, Core i5, still running Mavericks 10.9.5. I bumped the RAM to 8 GB and installed a 120 GB SSD from OWC. Like a new machine, very fast. I'll never go back to a conventional HD after putting a SSD in here. Put one in my Wife's Mini 2012 and even my shop iMac, 20" late 2006. This MBP was also cheap since I bought it 3 years ago with a water spill problem for $200.

"Diagnostics found no hardware faults."

Yes, I wouldn't expect either Apple hardware test would find a keyboard trace failure.

"Talked the situation over with the tech and she said in her experience most often the upper case is bad, the upper case being part of the keyboard.

I asked about the cost to replace the upper case and was quoted $174 and change."

Yup, Apple is not going to go to the trouble of replacing just the flex keyboard. These can be had for as cheap as $20 but from China or $33.11 for the 13" from Michigan:

http://www.ebay.com/itm/Replacement-Keyboard-with-Flex-Assembly-For-Apple-Macboo k-Pro-13-A1278-/121555358622?hash=item1c4d43939e:g:14sAAOSwUuFWueUO

It's a pain to do because in the Unibody, everything!, has to come out of the computer. Then there are about 50 tiny screws (Don't hold me to that number, they're really hard to count!):

that have to come out, then everything goes back together. I have done about 5 now. I also recommend using only new parts because I used a used one and it developed an "S" key failure. Like "ssssssss" and had to be replaced.

I had a problem as noted above with a single "s" key. It would fire untouched repeatedly and also keep firing after being pressed. Like ssssssssss. Took the keyboard membranes apart and found this:

There is an identical pad on the front trace and when the membrane is pressed the key activates. Not sure if it's resistive or capacitive but see that tiny hair in the lower right? That's what was causing the problem. Replaced the flex keyboard and the problem went away. 2nd time I'd done that but the first time I used a used keyboard but never again. It seems like a tiny hair that found it's way between the keyboard membranes.

Here's a picture of the front membrane contacts on a MBP that I posted earlier in this thread.

So as you can see the contacts here are all arranged and wired horizontally. Any crack in the trace will cause the downstream keys to stop working. (Not sure which way is downstream.)

Sometimes flexing the keyboard will cause it to start working again but a permanent fix involves replacing the keyboard. It's quite a pain to do the replacement due to the number of screws and the fact that everything has to come out of the MBP but the replacement keyboards are cheap now.

Hello MattyRay,

The following article provides some useful troubleshooting steps that can help resolve issues with your keyboard.

One or more keys on the keyboard do not respond

http://support.apple.com/kb/TS1381

Cheers,

Allen

Thanks for your reply! I tried:

• Without USB keyboard, the issue comes and goes on the mbp
• While it was occurring, I plugged in the USB kb, problem persisted on mbp but USB keys fired perfectly
• Left USB kb plugged in and worked on other things until the issue arose again; same results as before: mbp kb "D" key and neighbors lapsing, USB keys worked just fine

To better explain, here's more: While "it's happening," I am able to hold down the "D" key. Normally I would expect 1 D, a delay, and then a stream of Ds nonstop. Instead what I get is a long delay before the first "d" followed by a brief delay and then another "d" and then maybe a short burst of 3-6 Ds and pause and then another 1 and then delay, etc... However, if I get it to give a good burst, it may hiccup a bit before then consistently working again! There does not appear to be a pattern to it, and I strive to maintain constant pressure (not flexing or rocking the key or its neighbors). It's always only D-L from what I observe.

Apps I suspect might be messing with me:

• Tuck (really awesome, simple window manager by IrradiatedSoftware)
• Time Machine backup (it just ***** the life out of everything, doesn't it?)
• Chrome browser (Sometimes the issue appears to coincide with opening of a new browser ..)
• The Great Suspender (Chrome browser plugin which parks a tab to conserve resources)

...but I suspect it's not any one app but maybe some common thread messing with an OS level kb input scan or like Great Suspender freezing an operation at an inopportune moment.

Note: Nothing unusual in Activity Monitor like high CPU or something.. I believe a system restart clears the issue but it can return very quickly. I do restart with "restore windows," and my Chrome is usually 4 concurrent Chrome profiles and 12-25 tabs total across all.