2007 Prius powers back on after power off

[ctcdjc]

Recently our Prius has had a curious problem. Sometimes a few seconds after power off, all of a sudden, we experience something like an electrical system reset. The power comes on, the CD player sounds like it is moving CDs around, and the display comes up and tells us this is a new car. We lose all our radio stations and navigation system is set back to factory settings. This has happened about 6 times in the last month. Took it to the dealer today and they can't find anything wrong. Of course it didn't happen when they tried it. They said there are no codes being set. Tell us to bring it back if it happens all the time. About 2 months ago we were rear ended at a stop light- the damage looked fairly minor but it was $4K worth of repair and they mentioned something about having to do a lot of testing on the electrical system to see if it was working properly- so this may or may not have something to do with the problem. Any ideas? I don't want to get stuck somewhere because the electrical system is not connected properly.

[a priori]

Check to see if you have any corrosion on the posts of your 12V battery. It sounds like you could have a poor connection. If you disconnect and clean the battery posts (and connectors), you may find the problem goes away. (All of your presets and other basic information also will go away, so make certain to write down all of that info first!)

[Rokeby]

to PriusChat.

+1 on what a priori said.

IIRC, this is the second such complaint recently, both on 2007s. Hmm...

After your accident and repair, it would be a good thing to monitor your
spare tire well for water.

Damage to the rear end, especially the corners, can be the cause of
leaks around the tail light assemblies. They are held on by just two
nuts on studs; one metal, the other plastic. It is easy to over-torque,
even break the plastic stud. So with only minor deflections in the
bodywork, water gets in and like magic...

There's Water Sloshing Around in The Spare Tire Well.

Don't worry though, there are threads here on how to fix this...
think silicone caulking.

Why not give the rear end a hose test just to be sure?

Hope this helps.

[dogfriend]

Also, check the tightness of the 12v battery ground cable where it bolts to the body. If they repaired damage back there, they may not have tightened that connection properly.

[richard schumacher]

Or the battery itself may have been damaged. Have the dealer test it, or use the selftest procedure given here:
Checking 12v Battery Health - Hybrid Car Forums

[ctcdjc]

Thanks for the suggestions- I have checked the connections and they look ok- no corrosion and the ground wire connection is tight. Also ran the battery check and it checks out ok.
and no water (yet!) around the spare tire either!
and, the problem happened again yesterday... trying to narrow down when it does happen- like do I still have my foot on the brake or don't have it on the brake when it powers back on, etc. 4 drivers in the house and we've all experienced it at least once!

[dogfriend]

I found this thread that is possibly similar:

'06 Prius starts by itself

no definitive conclusion

[ctcdjc]

Still happening and with more frequency now- - sometimes it seems like it loses everything (navigation history/settings, radio, clock) and sometimes only clock and radio while the navigation history is still there. Yesterday after I turned the car off I sat there and decided, yes, it's off- got out of the car and attempted to lock the door- started beeping at me- wondered if I left my keys in the car- no, have them in my bag- and finally figured out the car had powered itself back on again after I exited! Still have not figured out any pattern to this other than seems like a short drive (15 minutes or so) is most common. My husband said he noticed a couple times that on pressing Power off, everything went black- that is the normal blinking dashboard signal went out completely and then a few seconds later the car powed itself on again.

[qbee42]

This sounds like a 12V problem. Have you ever replaced the 12V battery?

Tom

[ctcdjc]

no, haven't replaced it. I did do the battery check as suggested by Richard (#5). I will probably take it back to the dealer and have them check it again and find out about getting a replacement.