Totally strange issue this morning, that's happened once before.

Went to start the car, the doors unlocked, but then I turned the key and the whole dash went dark. The seatbelt light came on very faintly, almost like the battery was dead. I'm pretty sure the battery is good (although I haven't checked it with the multimeter yet).

So I start pulling fuses that seem related to the ignition, both interior and in the engine bay. Nothing really seemed to reset it - until finally I started pulling apart the rear hatch carpet to check the battery. As I was doing that, I heard the ding of my key in ignition, and apparently everything was back to normal.

Any ideas what could be going wrong? Maybe a ground issue somewhere?

Of course, both of these times it's happened right after my girlfriend drove the car.... totally unrelated, I'm sure

 

What did the last fuse protect?

Just reading the battery with a DVOM won't tell you if it is good or not, you need to remove it from the car and have it tested at a parts store or repair facility.

 

Wish I could remember what the last fuse I pulled was, I do know I was going through all the fuses in the engine bay when the power came back a couple minutes later.

Pretty sure the battery is fine because after the power comes back it exhibits none of the signs of a dying battery, but I'll get it checked out at a parts store to be sure.

 

Actually, I'm thinking this might be the immobilization system. The car came with a spare key but the wireless remote functions don't work at all. As I've been reading about trying to reprogram the remote, I've learned a lot about the transponder chip that is encoded to the car.

Both times the car's gone dead like this, my girlfriend was driving it with the spare key - that I haven't guaranteed is worked yet. Would the immobilizer kick in immediately upon trying to start the car with an invalid transponder? Or would it delay a bit and stop working after perhaps the first start?

 

Welp, this happened again. And weirdly, didn't have to pull a fuse to fix it! Can also rule out the "bad" key as haven't used that for the last few weeks.

So drove the car earlier yesterday and everything was working fine. Went to start it up later that evening, and it died again right as the key switched from the accessory position to the starter position. Didn't even crank over once I believe.

I left it overnight, then in the morning came back to find it still dead. Put the key in the ignition and turned the lights on, so I could tell when it came back on as I was pulling fuses under the hood. But when I came back with tools, the lights were on! All I did was open the hood and the cover for the battery in the trunk.

This leads me to think it's either the battery is bad (I'll be getting it checked tomorrow) or I have a ground short somewhere. Hopefully it won't be too hard to track down, as it's shorting out when starting it must be one of the main grounds.

 

Since it seems to recover whenever you go to look at the battery, I'd guess you've got a loose or corroded terminal or ground back there.

 

Think you might be right about the loose terminal! Went to get the battery checked today, and before I started pulling it out I noticed the positive terminal was slightly loose. Definitely not something I had noticed before.

Also the battery tested bad, so got a new one in there and made sure to tighten everything down extra tight. Didn't see any corrosion near the ground wire, so should be good. Hopefully this is the last time I have to update this thread, thanks for everyone's replies!