Dead 12 V Battery

Replace the 12V battery. After 4 years, it's due. Even if the battery was not the cause of the problem you observed, you are better off just replacing the battery now instead of waiting until it actually dies on you. Batteries only have a 3 to 5 year lifetime, depending on the quality of the battery.

 

That battery will run you about $300 at a dealer. There are some aftermarket options that require a little adjustments to work for about $100. Do a search and you should find the info.

 

I had an earlier post about this that is lost at this point. Fortunately I saved it as a Word file. See below. I think you were lucky enough to have the engine remobilized before the battery died. You'll understand once you read:

We had nearly the identical experience this weekend. It took two days to regain control of our 2005 Prius. I did a lot of digging and here is what I think happened to us and probably to you too. SOMETHING (radiowaves?) set off the anti-theft response while the car was just sitting in the driveway: lights start flashing, the horn beeps, etc... Evidently, it is supposed to shut off after a minute but in this case it just kept going until the auxiliary battery drained. Now, an additional response is immobilization of the engine (a lot of newer cars have this). So, as long as the car stays stuck in alarm mode, no amount of battery charging or boosting will get the car up and going until the engine becomes "remobilized". I have a 12V charger and I tried every permutation, under the hood and direct to the battery, that I could think of. There are various procedures described in the manual for stopping the alarm (within the one.minute) and you might think that they would work to get us out of this prolonged anti-theft mode. I’m pretty sure that we did some or all of these things in the course of trying to resuscitate the car. So I am not sure what caused recovery. I have called Toyota and various dealers and have gotten no solid answers to either of these key questions: 1) What caused the alarm to go off? Windows were closed so it wasn’t someone reaching in and unlocking the door. 2) What made it recover? This means that even if you are carrying a battery booster, it might not help. I am desperate to figure this part out in case it ever happens again. If anyone has some solid information on this…

Two other items related to this experience: 1) I have read in other areas of this site and in other sites about people leaving their cars for a week or longer and confronting a dead car. I wonder if the same thing happened to them and they just weren’t around to see it. Since the battery is so small, there’s a relatively small window for anyone to observe the alarm going off. I’d be interested in whether a simple charge got them going again or whether it was more complicated. 2) At the time our car died we had an important errand to run. We decided to push the car out of the driveway and onto the street so we could get to our other car. Well, you need some power to get the car into neutral. Simply charging the battery directly did not do this for us. We had to connect the charger under the hood (which pulls way more current for reasons the dealer mechanic could not explain) and then give it a boost before we could get it to go into neutral. The engine still wouldn’t kick in but at least we could push the car. Apparently there is no override for this. I’m not comfortable with this. It seems to me that, in addition to added inconvenience, it also increases the chance for serious damage to the transmission if the car gets towed by someone who doesn’t know how to deal with a Prius..

 

2002 prius 48,000 miles.


Two days ago I decided to charge my cell phone using the car battery. After 20 mins
I unplugged the charger and tried to start the car , nothing ! no power !

Called Toyota they said to jump start the car, a friend and I hooked up the two cars
and almost immediatly the crt came to life but still couldn't start the car, continued to
charge the battery for two to three mins and tried again. Car started instantly.

After running the engine for ten minutes I turned it off and waited 5 mins and tried
again with no problem satrting the car.

I drove the car to toyota and they performed a resistance check on the battery and
it passed all tests.

After two days I again had the dealer perform another test with the same results.

Needless to say no more charging of the cell phone with just the key turned to acc

Tom H

2002 Prius
2005 Prius

 

That settles it. I'm starting legislative action to ban on those $^@#& noise-making car alarms. Not only do they drive everybody crazy when they go off accidentally, they damage Prii. Curse those things! Curse them to all heck, darn it, heck I say!

Oh, and on another related note, I left my Prius on the street for 6 weeks when I went out to launch the latest XM Radio satellite. I came home, pushed the button and it started right up. I haven't had a problem yet!

Aerich the Rocket Scientist
Alexandria, VA

PS: I really do hate those car alarms. Can't we all just use the club?

 

Well, the alarm without GBS has no shaker switch, so the only normal way the alarm will go off is if an entry is compromized. This included the engine hood. If you don't have GBS and the alarm goes off spontaneously, you have electrical problems that should be investigated and fixed. Granted, this will most likely be easier said than done, since a problem like this is intermittent.
I believe drastic power fluctuations could cause the alarm to go off also. There is a TSB on the JBL amp not properly shutting off, which could cause a parasitic drain on the battery.

 

Our car is an early 2005 model - now being recalled for a "software problem". It seems possible to me that this problem could also cause what happened to us.

 

The 'recall' is to reprogram the ECM, that is, the engine control module. This rectified a problem where the engine appeared to fail to start. Has nothing to do with battery drain.

The connector might be, but I don't think so.

 

Where could I find info' My 12 v is dead, could i just buy a regular 12 v from walmart because the dealer locally is quoting $350? Is the battery special?