car won't start, no dash lights either
 

Car: 1997 Maxima, Automatic

So I crept through a puddle this morning and apparently splashed too much water into my car's engine compartment. Not sure how since I was going about 10mph but whatever.. the car instantly shut off, but had dash lights on still. I parked it and tried to start it again. It clicked and all the lights went off. Had no battery power. I pushed it off the road, and while it was rolling the dash lights came back on. I tried to start it again and did the same thing. Just a click and then no power. Had no power since then as well.

I put a voltmeter on the battery and it's got 12.7v. I didn't see a main battery fuse or anything, but I looked through the fuse boxes and didn't see anything out of the ordinary. Am I missing something? Any thoughts on what could cause this? It's been over 4 hours now, so I'd guess it should have dried out if there was any water still in there.

Thanks for any suggestions.

Check your negative battery cable. It goes from the negative battery terminal to a grounding point right under the battery tray and from there to a grounding point on the engine block. Check to see if any of the wires have come off due to age. it's happened to me before.

I was in there a few weeks ago and they all seemed fine. I'll look again, but I kinda doubt that's what's wrong.

Try doing the voltage check again, at the battery, while someone tries to start the car. If it drops below 9 volts or so you may just need a new battery. Certainly the water can draw current from the battery in all sorts of different directions especially along dirty paths between exposed + connections and ground.

Check the electrical box behind the pattery, also the two red plugs at the battery positive terminal. That is the feed for electrical power to the entire car.

All the fuses and fusible links in the box by the battery look good. Battery connections all look good including ground connection.

It's not even getting ignition power from the battery so turning the key probably won't have any effect, but hey, it's worth a shot.

Could the battery have a short in it somehow that it shows 12v at the posts but won't power the car? Doesn't seem likely to me, but I don't know.

Unplug each relay, fuse, and connection and blow it out or use WD40 (Water Disperser Forumula #40, Its true and intended purpose). Just looking is not enough. You got water in a connection and it is causing an open circuit or voltage drop.
The entire car is loosing power and I already told you where it comes from. Do some work and make something happen. We cannot fix it through the computer for you.
Are you running a CAI, and how high was the water?

By "looks good" I meant I checked them, and not just looked at them... sorry for the bad terminology.

I did actually get it working though, and I'm not sure why it worked.

I hadn't disconnected the battery until recently, and when I pulled the negative cable it fell back on the post. It made a small spark and little crackle noise (like electrical connections sometimes do) and made me wonder, so I reconnected it and tried it and I had power. Could that have maybe reset the ECU or something? I'm not sure why that actually fixed it....

Thanks for everyone's suggestions. I appreciate the help.