Prius moved while parked and no one inside

I found this:
2007 Prius Turning on By Itself | PriusChat

 

Never heard of that before. WOW!! The most plausible thing I can think of is a combination of a flakey power button and there's an unknown-to-you fob hiding in the car somewhere. But even that doesn't really add up if the gen 2 is like the gen 3 in that it won't let you lock the doors with a fob inside.

Good catch on that other thread @schja01. Combo meter sounds plausible to me, but it's a guess on my part. I wish the OP on that one had reported back what they finally did. Or the second one in that thread with the same issue.

 

Ah, the new self driving model is finally here

 

Christine is back!!

 

Google is my friend.

 

There's usually some "text message" posted along with the major warning lights

Don't rely solely on the park setting, use your foot brake, too

 

Is your driveway flat, or sloped? Is the surface now dry or slippery? I once had a chev parked in a sloped driveway in park. It had been driven at highway speed for about 45 minutes, so the tires were warm. When the tires cooled off it slid backward down into the street, probably moved 75 feet. Turned out the driveway surface was frosty, so slippery. Bizarre but it happens.

 

‘Jerry, I think it moved!’

 

Disconnect the 12v battery when not in use. Leave one of the rear seats down to allow easy crawling in and plugging in the 12v battery!

When in park, the hybrid system will periodically charge the HV battery; this does result in the car moving back and forth an inch; the transmission lock prevents anything worse happening, but this is normal (or maybe not but it always happens with my car).

If the car was in neutral when warming up, it could have rolled back. It would give a red triangle when you got in, all the way until you closed the door. In fact, the red triangle cannot go away of its own accord if there is an actual fault (at least not without a number of shutdowns and restarts). The Prius also makes a continuous noise when the high-voltage battery is low, but the car is in neutral, because it can't charge the high-voltage battery unless in park (or drive).

I think the cold conditions led to the parking brake not giving enough force - if the car was in neutral this is what would have happened and would explain all the sounds / warning triangle.

If you are worried about the safety of children, obviously get wheel chocks and also disconnect the 12v battery until you are sure what happened.

Hope this is of help

 

Sounds like the parking lock mechanism got disengaged some how. This is assuming you did NOT put the car into neutral.

FYI, it is a good safety practice to always engage the parking brake for all cars. The transmission/transaxle parking mechanism can fail (albeit it rare), thus the back-up parking brake (if engaged). The probability of BOTH mechanisms failing would be VERY RARE.

Also, vehicles with rear drum brakes, regular use of the parking brake helps to keep the rear shoes self-adjusted. I know regular use and self-adjusted is an oxymoron, but that is the strange reality of brake systems with shoes. Reason for this is, engagement of the parking mechanism will take up slack. Depending on how much slack is taken up, the adjusting mechanism might move one notch over. This will help keep the shoes a more optimal distance from the drum. Unfortunately, the self-adjusting mechanism on brake drums SUCK. Thus the need for regular/periodic inspection/adjustment/maintenance. Disc brakes are much better at self-adjustment.

Drum brakes are CHEAP and are adequate for certain vehicles. Thus their continued existence into the 21st Century. However, fewer cars and trucks are employing them as the model years progress. I’m sure some time in the near future drum brakes will no longer appear on new cars/trucks. Wish the US Gen2 Prius had rear disc brakes instead of drum.

 

Well really this is just a total red herring as the OP's case is totally different scenario. Note particularly what he says here:

So the car did not start by itself, the OP started it.

The issue is quite simple, do not leave the car running and unattended without the foot operated parking brake applied.

 

Sell the car.

 

Unfortunately the OP created the PriusChat account, made this thread, but unfortunately (at the time of writing this) has not logged in since.

The obvious conclusion is that the OP hasn't had the chance to read our good advice

 

yeah, o/p left the car in reverse, got out and went in the house. too embarrassed to come back.

not the first to report getting out of the car while still in gear.