check this thread
http://www.priusonline.com/viewtopic.php?t=6001&highlight=
I had a similar experience and so have others. The best explanation thus far is that the problem is being caused by the ECU.

 

I doubt it is the ECU, he isn't getting lights. I'd say the aux battery is not holding a charge. Have a capacity/charge hold test done on it, keeping in mind it is only 30AH or so battery.

Now if he was able to get into Ig On but not READY, or could go to READy but then gets a MIL, and the ICE won't come on, then maybe it is the ECU.

 

The 12-volt battery is worn out.

What you described is exactly what happens when it's drained, barely able to hold a charge anymore. And after 5 years of use (with the security system running the entire duration), it's due time to for replacement anyway.

That's all. No big deal. In fact, you can even upgrade to a larger capacity one while your at it.

 

And will a 2004 show the same kind of symptoms when the 12V is dying?

I thought all it needed to do was to boot the computers, so as long as it wasn't dead it could limp along...

 

classic battery

Here described one alternative for the classic 12 volt battery

http://home.comcast.net/~dldorrance/battery.html

and another site selling the components

http://elearnaid.com/12vobaforpr2.html

It is not possible to limp along w/o a working 12 volt in Prius. The bootup procedure typically includes an electric motor pressurizing the brake fluid, so there is a limit to a minimal Prius battery. A 7 amp hour gel cell will do in a pinch, anything less than that, uncertain.

Eventually the new model Prius will need replacements. Not sure about the aftermarket options here because the terminal posts are reversed.

Or, you could buy the OEM part from Toyota.

DAS

 

Well, it is theoretically possible to start up without kicking in the brake accumulator pump, since all you really need is the brake pedal switch engageing, but you'd have to have a really light touch.
But then, to get to READY, where the DC-DC converter would engage, you have to get through Ig-On, which powers up quite a few things.

So, yes, takes a bit more power than one would initially think.
Sorry, I tend to think things through as I write.

 

Hi. I am a new (used) Prius owner and new to this board. I purchased my 2001 Prius November of 2005 (from a Toyota dealer) with 88,000 miles and also purchased an extended warranty.

Six days after purchasing, the check engine light came on. The catalytic convertor had to be replaced.

I'd be willing to bet that the codes for the catalytic converter were related to:
http://autos.groups.yahoo.com/group/toy ... 015-02.pdf

US TSB EG015-02
Aug. 2, 2003, M.I.L. "ON" P1436-HCAC Bypass Valve Improvement, 2001-2002 Prius. (road salt may cause issues with valve. possible fix is to replace the Front Exhaust Pipe Assembly if any shaft binding is evident.)

The front exhaust pipe includes the catalytic converter. I had this fixed on my car (several check engine light cases, but the lights always cleared before I could get an appointment with the dealer, and supposedly the codes had cleared themselves by then, but finally a year or so later the lights stayed on for a week). It is noticable as a quick squeak or a chirp. The first few times I had it I thought that maybe I had backed over a small animal after starting my car. Later it happened most every time I started my 2001 Prius, and later when I was accelerating up a particular hill once the traffic light turned green. It would've been a $1600 part alone, but since it is covered under the Federal Emissions Warranty for 96 months/80,000 miles, it was free for me.

I took a 1200 mile round trip the beginning of December. About 500 miles into the trip I went to start the car and nothing happened except a "click" click" sound. No lights at all came on. I waited about 15 minutes and tried again and got the "clicking" sound and the airbag light and ABS light came on. I tried again and the car started right up. This happened 3 times during the trip. Two days after being home the same thing happened only it took about 24 hrs for the car to start up again. The car was towed to the dealer. They claim that they could find nothing wrong with the car. Today the same thing happened again...after waiting about 10 minutes the car started right up. Any help or suggestions would be greatly appreciated.

Sounds like the 12v battery isn't able to hold a charge (discharges too easily). You need 12v power to boot up the computers (and the brakes), which will then connect up the hybrid battery which will then take over the charging and actually starts the gasoline engine.

I suggest the links available here:
http://autos.groups.yahoo.com/group/toy ... 072738257/

 

Update

After 4 months of the car not starting periodically and 3 visits to the dealer, they have come to the conclusion that it is the accessory battery that is bad. Why would it take the dealer that long to decide this is the problem? They claim that the battery has tested fine every time up until yesterday when I had to have it towed in again for failure to start.

 

Re: Update

...Why would it take the dealer that long to decide this is the problem?...

Because unfortunately you are dealing with a below-average Toyota shop. I am sorry to say so. Probably they will offer you the replacement battery for $200 plus. That battery can be purchased from Conicelli for about $70:

http://tinyurl.com/p22uf

Which is new information since the aftermarket 12 volt batteries were discussed here earlier. Perhaps that Conicelli price will cause your shop to match the price. If not, I hope you see that it is not at all hard to correct this small problem.

Please keep us informed, and are there any other Toyota shops near you? I want you to change horses.

DAS

 

I continued to have problems with the car even after having the accessory battery replaced. Two different Toyota shops told my daughter and I that there couldn't possibly be anything wrong with it because no codes came up and of course it always worked when in the shop.

Well 2 1/2 weeks ago (106,000 miles) the mark of death came up on the screen. It was taken to a Toyota shop immediately. (on a saturday) 2 hrs later the service manager came out and said that 4 different codes came up and that we would have to wait until Monday for an opinion from their supposed 3rd Prius trained mechanic since the 2 on duty could not make the call as to what was wrong.

On Monday I got the dreaded call that the HV battery had failed. Go figure. I have been complaining that something had been wrong for months and now I was 6,000 miles over warranty for the battery....so...of course the battery was replaced.

The car was in the shop for 13 days, I pick it up and not even 1 mile away when I was coasting and getting ready to put on the brake, the car just started shaking/vibrating like it was in an earthquake zone. Of course nothing showed on the computer screens that anything is wrong, so back in the shop it goes.

Any suggestions would be greatly appreciated. The car did not shake or vibrate prior to being in the shop for 13 days and I am at my wits end with this car. I have yet to receive a call from the shop to let me know what is happening this time.

 

1) The first problem described was the 12V battery. Your description matches many of us that have had the exact same symptoms.
2) I have experienced the shaking you described in my 2001 on very rare (1 per year) occasions. It was solved with a cycle of the brakes or a tap of the accelerator pedal (be safe here!) and did not affect the driving. It was definitely not normal. It baffles the dealer as much as me. No trouble codes and definitely not reproducible for the next 1000 attempts. Keep a record of every time it happens. The 2001 Prius does have some history of the acceleration pedal not working smoothly and it could be related to this. There is a problem called the "big hand syndrome" where the Prius suddenly slows down with the warnings notification to go to the dealer appears. You can continue to drive, but not very fast. This problem required replacing the gas pedal. Since then no shaking (but time will tell).
3) If at all possible see if you can get the "trouble codes" from the dealer, if there are any. These are called DTCs (Diagnostic Trouble Codes). Many on here can tell you what these mean.
4) Please go to a different dealer if you feel unsatisfied (and I think you are). There are some great technicians out there, but not every dealer has one. You may have found one that is lacking the good Prius technician needed. ("There can be no problem since there are no codes" is nonsense. There is no code for a flat tire, and that's a big problem.) The 13 day delay needs an explanation.

 

Thanks for the reply Fl_Driver.

I received my Prius back today after another 48hrs in the shop. Of course the problem could not be replicated and I was told the car is operating within manufacturing specs at this time.

I did get the DTCs that the dealer said were related to the Hv battery.

P3006 and P3011

I will be trying a new Toyota shop with my next oil change and see how that goes.

 

For followup:

P3006 - Battery SOC (State of Charge) is uneven. This indicates that the highest voltage module of the HV battery was at a notably higher voltage than the lowest voltage module. This is the same error that cause my HV battery to be replaced.

P3011 - Battery block malfunction. One of the modules was indicating malfuction. (Temperature?, Voltage?) This is more significant and may indicate a developing problem.

The dealer replacing the HV battery was justified. There may be experts at other dealers that may be able to solve this without replacement, but this would be unlikely.

Hopefully, there should be no problems for some time.

 

I forget who, but there is someone here who has been rebuilding accelerator pedal sensors.