Theft deterrent

Oh.. I get to be the one to say this this time. Are you still using the original 12v battery? It'll do odd electrical things like this when it gets old... and yours would be old if its original.

 

I think he meant your 12v battery in the back of the car. There are many threads here about 12 volt batteries going bad around 3 years in (some sooner, some later).

If you need a quick fix for the night, disconnect the negative cable from the 12 volt battery where it bolts onto the car (not where it connects to the battery). This will kill all power to the car until you reconnect it. You will loose your radio presets, the auto up and down on the windows will need to be reset, and I think you will loose the current average MPG.

Your call if that is better then going outside a few times in the middle of the night.

 

No. BallanJ is not talking about the key fob battery. He's talking about the 12 volt battery in the hatch area on the passenger side behind a large black box. If you're still on the original, it's almost certainly in need of replacement now. You can test it via http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html. Best to try it after the car has been left overnight or at least 8 hours.

As for the fob, that's a separate thing. Do not pry it open. Just pull on the mechanical key release, remove the key and then slide cover off. Putting your thumb on the Toyota logo might help. You'll see 4 screws. You'll need a small Philips screwdriver for that.

 

1. The fob battery definitely is not the problem. BTW, the fact that the red LED lights up when you press a fob button is not evidence that the battery is good from the point of view of providing an adequate signal for the Smart receivers in the Prius. It is merely evidence that the fob battery is not totally dead.

2. It's possible that the 12V battery might be a problem, if the voltage is sagging down while the car is IG-OFF and this is provoking the alarm to trigger. The 12V battery is located in the hatch, right rear corner, under the triangle-shaped hatch floor piece.

3. I doubt that you can access the electrical contacts in the door switches without considerable trouble and effort.

4. Since you won't be able to visit the dealer for a while, the most useful thing that you could do in the interim would be to find and disconnect the alarm horn. If you can't do that, then disconnect the 12V battery. You can either disconnect the negative cable where it connects to the body, or else the positive cable where it connects to the dedicated positive jumpstart terminal within the main relay/fuse box. The advantage of doing the latter is that you won't have to crawl into the hatch and find the mechanical hatch lock release when it is time to reconnect the battery.

Good luck.

 

Was the new battery charged before they installed it?

Tom

 

Unless you feel like your Prius is a serious theft target, I would be inclined to deactivate the alarm (by disconnecting the alarm horn.)

I'm not sure how the dealer will be able to help you with that issue, if the alarm doesn't activate when the car is parked there.

 

I have had a similar issue with my 07' V. Turns out it was my company's Nextel Radio/Phone that was left in the car it would go about 5 minutes between alarm triggers which is the same interval the Xmobile tracking softwre installed on the phone was set to report/update driver location.
I have also had it happen when my friend misplaced his personal nextel in my car(no tracking software) and we called it and set the alarm off announcing to me that the phone was in the car.
Nextels produce some sort of RF interference that trips a sensor in the anti theft.
I would assume other strong RF signals could do the same.
You may have some sort of tracking device installed in your car if it is leased.
Here in Miami just about all new leased vehicles and some financed cars have "LoJack" there are allot of brands most use cellular.

 

Did you ever find out what the issue is? I am having the same problem. New Battery and FOB.