BRZ spontaneously won't start
 

I've been having this issue for a few months now and have finally narrowed the "symptoms" down as much as I can. Basically about 50% of the time that I go to start the car it won't start. I have keyless entry and push button start, and when I push the clutch in (all the way) sometimes the "green key" indicator simply won't show up on the dash, and the car won't start when prompted. Sometimes the green key pops up immediately (solid) and the car starts just fine. I'm assuming there's some problem with the clutch and the electronic path which shows the clutch is being depressed to allow the car to start, but I can't purposefully demonstrate it as the car has a mind of its own in this way. Any ideas what's going on? The only way to "fix it" when it gets like this is just mess with the clutch for a good 5-10 minutes and then miraculously it'll show the solid green key and then start like usual. I've had the car for 2 years and this just started relatively recently.

Oddly at first I thought it was some problem with the battery and took it to Autozone and they found a problem so the dealer replaced the battery, but it didn't help the starting problem at all.

There is a switch that gets depressed by the clutch pedal itself which tells the car you are pressing the clutch. The first thing I'd do is peek under there and make sure that switch is properly adjusted. You can look around on the forums for photos. Find a DIY thread for adjusting clutch pedal height (or spring removal) and it should have a picture of it.

if its still under warranty. Take it back ASAP

Have you checked the battery of the key?

I popped my head down there the other day and couldn't find it but I'll look online, thanks.

I have not. Maybe I'll start using the other key and see if it stops.

It is and I already did but they were just as lost as me but I've narrowed the problem down more. They just replaced the battery which didn't help (odd coincidence that it was also dying?). I will take it in soon if I can't fix it as I have another 9 months on warranty I believe.

So I'm watching this video and was down there for a bit and couldn't find anything that might be the problem (not sure what I'm looking for). I tried a new key and it did it again.[ame="https://www.youtube.com/watch?v=ScZFQ0j5beY"]BRZ/FR-S Clutch Pedal Adjustment DIY - YouTube[/ame]

Does the door unlock from the proximity of the key? Does all of the interior stuff come on when you hit the start button but the car not start?

What color is the key icon when the car doesn't start? Is it yellow?

Does jiggling the steering wheel have any affect on the car starting?

What you're describing almost reminds me of the thread below.
http://www.ft86club.com/forums/showthread.php?t=109052

Key works fine for everything. All lights and everything works when I hit the button. The car will NOT start unless the "green key" in the dash is solid. When it does NOT start there is NO green key, there is no yellow key, there is nothing to signal anything. It's like I'm not pushing the clutch in basically. You'll notice on a "normal" BRZ the light will turn on solid when you engage the clutch. I don't know how I get the "green key" to show up. Sometimes it seems like I get it from messing with the wheel or the shifter or the clutch. It seems so hard to replicate it and even harder to fix when it happens.

The guy in that thread seems to have a different problem as his "green light" prominently showed while mine wont.

clutch safety switch. Adjust the clutch down a little and see how it goes. If that doesn't fix it, adjust it up some and see if that fixes it.

the switch could be bad too, but most likely it is just out of adjustment. Grab a wrench and fix your problem.

Where's the switch? Down there by the clutch? I just don't know when the problem is gonna happen so it's hard to tell if moving the clutch around will fix it or not since it's sporadic. It's been hot as hell here (over 115) and I wonder if it's caused some issues with the switch/electronics because I've never messed with the clutch.

Well for prosperity's sake here's what the switch looks like (I think?)
http://www.rockauto.com/info/903/1S14060.jpg

have you made sure that your steering wheel was not locked prior to starting up the car? with your steering wheel locked, you will still have power to your accessories but just the starter won't turn I believe. some people would accidentally bump their steering wheel when getting in and out so they do not realize they locked it up.

I would replace the battery in the key before getting a wrench anywhere near the car. That may not be the problem, but it's really cheap and easy to rule it out. It would be really stupid to start mucking with other stuff only to find out in the end that it was just a tired key. Generally, when troubleshooting, you rule out the easy shit first.

This^
Read pages 79 and 167 of your owner's manual.