2005 Prius beeps when door is open, then won't start

Your car needs a new 12V battery which is located in the hatch floor, right rear corner.

The battery state of charge gauge that appears on the MFD relates to the traction battery. That gauge tells you nothing about the 12V battery's status. Therefore, it doesn't matter whether you see 6 blue bars or 7 green bars, that is irrelevant to the 12V battery.

Also, the traction battery SOC typically will be kept at around 5-6 blue bars, unless you drive down hilly terrain. In that case you may find that the SOC will increase to 7-8 green bars.

I recommend that you check the terms of your extended warranty to see if the 12V battery is covered. If not, then just buy a replacement from your dealer's parts counter ($139 MSRP) and install it.

If the Prius beeps at you as you try to leave the car, that is an indication that something is wrong. Most likely, the car was left in ACC-ON mode which could happen from READY if you depressed the POWER button twice (instead of once.) That would explain why the car would not start the next day.

Once the 12V battery has been discharged, it takes a very long time for the battery to be recharged. I usually suggest that the owner allow at least 8 hours where the car remains in READY mode before the 12V battery can be considered recharged (if the battery is in good enough condition to be charged.)

 

No.

Assuming that you have another vehicle available for use, you may want to spend part of today finding the 12V battery and removing it, so that you can quickly replace it tomorrow after a replacement is in hand.

 

I recommend that you call the dealer's parts dept when it opens on Monday, to ensure they have the battery in stock. It is certainly possible that an individual dealer may be out of stock, but hopefully you have more than one Toyota dealer in your local area.

The 12V battery part number is 28800-21170.

 

Or you could install this battery (and required installation kit), far less likely to become discharged or die an early death. Thes guys ship very fast, took 3 days all the way in Guam, lots of folks on this site have reported next day delivery.

Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 10

 

The exact same sort of problem is happening to me. It's happened several times. It just happened again this morning.

So if the car was accidentally left in ACC-ON mode, then a new battery might not be needed, right? How do I tell if the car is in ACC-ON mode?

I've been paying very careful attention when I get into the situation (where the car complains about the door being open even though it's off) because it definitely seems to be the cause of the dead 12V battery problem.

Once in this state, I've tried turning the car back on (putting the key back in, putting my foot on the brake, then pressing "on"), then turning it off (and verifying that the touch screen is off). But the car still complains about the door being open when the car is supposedly "off".

Is there anyway to get a diagnostic of what the car thinks is going on?

Is there any diagnostic for when the 12v battery voltage is low (eg., the battery light on regular cars).

Thanks
Ben

 

Hi Ben,

Since your car is 6 years old, if the 12V battery is original equipment then do yourself a favor and replace it now, rather than waste time trying to eke out a tiny bit more life from it - and risk being stranded who knows where, when the car refuses to start.

The car is in ACC-ON mode if the instrument panel warning lights are off, but the MFD is on and the stereo can be turned on.

If the Prius gives you a warning beep when you try to lock the car, make sure that 1) the car is IG-OFF and 2) that all doors and the hatch are closed. The hatch especially can appear to be closed when it is actually open. If you have the hatch light switch turned on, then by looking at the light you can see whether the hatch is actually closed or not.

The battery warning light on regular cars does not tell you that the 12V battery is low. It only tells you that the car's charging system is not working, typically because the alternator has failed.

A quick way to assess the 12V battery is simply to turn on the headlights and see how bright they are. If dim that is strong evidence that the battery is discharged.

 

Ok, thanks for the info. I'll go ahead and get the 12V battery replaced. The next time I get the door open alarm when the car is "off", I'll double/triple check that the car is not in ACC-ON mode, and that no door open lights show on the dashboard.

Ben

 

Just a note on the car sometime beeping when it's turned off and I open the door. This just recently happened. The car was definitely off. There was no display on the touch screen and the cigarette lighter had no voltage (I have a voltmeter plugged into it). It's sort of like the Prius thinks the key is left in the lock, except that the beeping is faster in this case.

Once I get into this weird state, if I start the car and let it run for a minute or two, then shutdown, I think that stops the door-open-beeping problem.

I'll replace the battery in anycase.

Ben

 

Hi Ben,

I also suggest that you replace the fob battery (CR2032) if this hasn't been done recently, to rule out that possibility as a cause for the beeping.

 

New battery option now available form Optima that is a drop in replacement (no modification needed)! Part number is 8171-767. My '05 did the same thing to me over the weekend. When we came home Saturday it beeped when we opened the door. Didn't think much off it until it wouldn't start on Sunday. Had to jump it in the garage. I researched the battery and found this apparently new one from Optima and also the Toyota option. Turns out the Toyota has less cranking amps, lessor deep cycle capabilities, and only a 1 year warranty vs. 3 years with the Optima. Decided on the Optima and found it at Batteries Plus. I saw it cheaper online, but since it was my first time, I didn't want to mess with the installation. They sold me the Optima for $199 with free installation. The dealer wanted $155 + $50 install. The guys at Battteries Plus told me this Optima battery is fairly new and prior to that there wasn't really a option to the OEM that didn't require modification. Go to Optima's website and use their battery selector tool. Hope this helps.

- Mark

 

I just ran into this exact same problem: "Prius beeps when door is open, then won't start". I have a 2008 Prius. I have no idea why the beeping was happening, but it did the beeping the day before and I was able to start it and ignored it. This morning the car would beep but it didn't start. I then found this thread and decided to jump start it. Voilá, car started. I drove to office (20 minute drive) and 8 hours later to get back home I had no trouble starting the car. I'll note that I've disabled the smart key for the time being just to make sure the 12V won't be getting discharged. I'll be re-enabling it in a couple days.

It is to be seen if I'm going to need to replace the 12V soon or not. Any suggestions on how to know if the 12V battery needs to be replaced? How long does the 12V battery generally lasts? I almost always keep the car in either the garage at work or the garage at home.

I just found the answer to my question on this youtube video to read the status of the battery:

 

^^^
I didn't watch his whole video, but he's got his terminology wrong. When he says "accessory mode" (all dash lights on), he's in IG-ON mode.

Please run the test at Weird stuff happening? MPGs dropping? Test The Battery | PriusChat after the car has sat MANY hours or overnight. Please tell us the 3 values (not just 1). Don't go changing the battery first until you tell us the values...

If you have HIDs, you can avoid unnecessary cycles on the lights by toggling between off and parking light positions.

Weird stuff can start happening w/a low or bad 12 volt. Don't waste $ on having a dealer "test" the 12 volt (07 Prius Dead - Any Guesses? | PriusChat). If you're on you're original 12 volt, it's likely near or at end of life now.

The 12 volts seem to last 4-6 years. Since you're in a hot climate, I wouldn't be surprised if they're on the shorter side of lifespan.

 

Ok. I just ran the test after the car sat overnight. I get readings of 12.0V, 11.7V and 14.0V. Based upon that other thread, looks like I might be on the battery going bad side of the spectrum. What do you think?

BTW, what does the (NL) and (NAH) mean?

 

Replace the 12V battery now.

NL is a two letter code assigned by Toyota for the 2006 model year option package 7.

2006 Toyota Prius Options & Packages Prices - Motor Trend Magazine


NAH means Nissan Altima Hybrid.

 

Just for the record, I procrastinated and then I was out of town for about a month. I got back and to my surprise the car started with no problems (luckily, I didn't forget to turn off the smart key system this time while I was away). However, now the first reading of the three is at 9.7V, and it didn't get much better after driving the car around for a week. Because of that I have kept the smark key system off, and I really miss it. Every time I get to my car I don't know if it is going to start or not.

This weekend I'm planning to get that 12V battery replaced. Is this the best thread on instructions for doing so: 12V Battery Replacement-- A Preemptive Strike | PriusChat ?

Does anyone know of a better one?

Thanks,

 

Go to the 6 minute mark on this video. Very clear instructions with helpful tips.

 

Thanks for the link to the video. That's a very good video. The only piece of information missing is on the hard to reach and easy to drop screw. I used duct tape to get it to stick to my tool, and that worked pretty well.

Now it is time to re-enable the smart key and re-configure the radio stations.

For the record, I got the OEM battery from a dealer for ~$210 with taxes and fees included. A different dealer in town was about $60 more expensive. Online was not that much better, so I bought local.