Why does my Right arrow key type the number "8" and the Up arrow key type the number "9"

Hi benmurray37,

Welcome to the Apple Support Communities!

For this situation I would suggest a few different steps to isolate and resolve the issue. Please follow the steps listed in the Some keys don’t work as expected section of the following article.

One or more keys on the keyboard do not respond

http://support.apple.com/kb/ts1381

I hope this helps,

-Joe

Right so it could be that these kinds of problems will continue and unfortunately get worse. Here's a post I put up explaining how these membrane key boards work:

Spilled water on my MacBook Pro! Yikes! Please help!

So if something got in there it could be that it's creeping around and other keys might eventually be affected.

I just replaced a top case in my 1011 MBP 13" and another in a 2008 MBP 15"

I'm beginning to feel that these MBPs are sensitive to any kind of liquid on the membrane. If you look at that post it doesn't take much, .5 mm in that case I posted.

how did you fix that?

Thanks for this very helpful article, Joe.

I'm having the same issue as Ben—and am wondering, Ben, if you were able to fix the problem? I followed all 10 steps in Joe's article and when I got to the last one, found that those keys were still typing 8 and 9 in the Terminal. What does that mean? And is there any other way to fix this?

I'd love to have those arrow keys back!

Thanks for any help you can give.

So if you can't repair this problem with a software fix it must be a hardware problem.

These keyboards use a matrix array to determine which keys are pushed.

Here's a pic from a 2011 MBP 13"

http://s291.photobucket.com/user/spudnuty/media/FrontTracesMBP201113quot.jpg.htm l

So you can see from this that the arrow keys and the "8 & 9" keys are interconnected in ways you wouldn't expect. What I'm thinking is that there's "cross talk" in that congested area with the vertical lines. That's where the front and back traces interconnect.

Thanks so much for this helpful graphic!

I've discovered that the functions are definitely interconnected: My arrows type numbers and also work as arrows at the same time, and the number eight and nine now function as right and up arrows while also trying the numeral. Also a new discovery this morning: the equals sign is working as a six AND an equals.

Does this shed any further light on the issue / confirm that it is a hardware problem?

Thanks for all the insight, folks.