I have a 2012 4runner limited, rwd that I bought less than a year ago. Since the first month, I have had this very wierd problem, one in which the dealers keep saying they don't see anything wrong. Let me explain the problem:

First off, let me start by saying this happens randomly. What happens is that while driving, multiple lights come on. Those lights are the slip indicator, passenger airbag off (even when someone is sitting there), and the SRS warning light. When this happens, the car will continue to run fine, but the inside lights will no longer work. When I finally turn off the vehicle, the entire vehicle goes powerless. Doors, locks, lights, etc... nothing works.

At this point, if i wait it out, it sometimes comes back on its own. However, recently I have at least been able to restart the car by putting the back of the remote to the start button. Once restarted, the lights remain on.

I have taken it to the dealership multiple times, and they always say everything looks fine. I have replaced the battery in the remote, and that didn't work. I'm at a loss now, so any help is greatly appreciated. Sorry for the long post.

When you say once restarted "the lights remain on", do you mean the various warning lights(TSC/VSC, SRS, etc.)? Or do you mean that the interior lights are working again?

If I am understanding you correctly, you're able to start the vehicle if you hold your smart key to the dash, which suggests that the vehicle battery (and connections at the terminal) is fine; and possibly the circuit powering the RFID receivers on the vehicle end is not getting power.

Have you ever had any collisions repair done where a wire harness might have been touched and/or have you ever had electrical work done on the vehicle? If I had to take a wild guess, it sounds like a loose wire some where.

Perhaps just to rule out as many variables as possible, could you take a peek at all the fuses under the dash (and under the hood) to make sure they are sitting in there nice and tight? While you are at it maybe just take a second look at the battery terminals as well to double check that it's making a good connection.

Also definitely change dealers and if possible burn that dealership down. I mean I understand that the problem may not be easily reproducible, but to disqualify something that detailed and then say nothing is wrong is inexcusable in my opinion and also invalidating of the customers experience.

Grounding wire?

My Tundra did this a couple times - the best I can posit is that when the system voltage drops below a certain threshold, the computers will drop out intermittently and cause some sort of fault. I had the same deal happen with shutting the truck off - I couldn't restart it or use any accessories until after what I assume is a 2-5 minute "powerdown cycle" for the computers. It seems like after they've powered down, the whole system resets itself if it no longer notices an abnormal voltage condition.

I managed to fix it, though I'm not 100% sure how I did it. I load tested my battery, and it was fine. I cleaned my battery terminals, and the problem still persisted. I narrowed it down to the alternator at this point. I bought a shiny new alternator, climbed under the truck, struggled with pulling the damn serpentine belt, pulled the electrical connections on the alternator, then lost all patience - the engineers decided that mounting the alternator at the BOTTOM was the most efficient, and that routing power steering lines right in front of the f*cking mounting bolts was smart too. My patience wore thin, and I decided f*ck it, I'll take it in to have the alternator changed. I reconnected the power connection and the ground cable to the alternator and went on my way. Long story short, I never did book an appointment to change the alternator because I never had the problem again and it's been over a year now. The best I can figure is that the electrical connections on the alternator were just dirty.

So, to review - I'd start with load testing your battery, cleaning and tightening the connections, and pulling/cleaning the electrical connections on the alternator. See if that works, and you might save yourself some $$ on getting it looked at.