Battery flat & manual key won't work!!

I have read multiple times on here that you have to turn the mechanical key much harder than you think you need to.

 

I seem to recall some say something about pulling the handle out a little. I too seem to recall that the keylock has been reported to be sticky when the 12 volt is dead.

I have never experienced it myself, so I am not 100% sure what really needs to be done. Hope you get it sorted.

 

Locksmith? They usually have tools that can open any car door with zero damage. Expensive? Yes, but cheaper than a broken window. Once inside, replace the auxiliary battery first.

 

I use the manual key regularly and it doesn't take much force. Sounds like this is the first time the lock has been used in 6 years, so maybe it's a bit tight.

When the weather gets on the hot side, I've been known to leave the car in READY at a parking lot. It's really nice to come back to a car with the A/C maintained 70 degrees. I turn off the screen, set the parking brake, and shift to Park. Then exit the car and lock it with the manual key. Several times people have asked why the car was running, and I explain that it does that for a few minutes every 10 minutes or so. The electric air conditioning is running, and the engine runs intermittently to recharge the battery. Everybody so far says something like "cool". Not one lecture about "leaving the car idling".

 

Hobbit wrote up a lengthy report on cleaning and lubrication of the lock and cylinder. I have noted that other's have mentioned that if the 12 volt is run down, it does take more force than normal to turn the key to unlock the door.

There is a wealth of information that can be gleaned from it.

Prius door lock

Ron

 

I just had total failure of all electrics overnight on my late 2011 Prius, at 24000 miles. No warning, door locks wouldn't release, and I had the posted problems using the mechanical key. I had a Prius before this one which had no problems in 6 years, so I was baffled. Dealer was totally unhelpful - said unless I delivered the car to his premises he couldn't help.

When I finally got into the car using the mechanical key, lots of WD40, and as much force as I dare, the electrics were completely dead. It looks like the auxiliary battery might have failed completely - and that means that the transmission is locked, so that the car can't be moved. The recovery guy managed to start the engine after three tries using a jumper pack (and now I have heard that this is not recommended by Toyota as it can damage the main electronics). When the engine fired up, everything went berserk - alarm banging away and the dash screen display that I have never seen before, some sort of initial boot-up menu. I have also heard that Toyota are aware of the auxiliary battery problem but if it can be charged overnight, they won't replace it under warranty.

I'm worried that there may be an intermittent sneak circuit which discharged the aux battery overnight. I am certain that there was no unusual load on the battery overnight to explain the loss of power. Now, if the battery charges up OK, I'll be none the wiser, except I will know that this problem could crop up at any time, which leaves me with little confidence in the car's reliability from now on.

Has anyone had a similar experience and if so, what was the outcome.

Help !!!!!

Ian Bruce

 

1. You probably should post in the Gen 3 forums instead of Gen 2, since you have a 2011 Prius.

2. Regardless, if you are concerned about quiescent current drain, I suggest you remove the 12V battery negative battery cable. Then hook up a digital multimeter set to read current, connected between the negative terminal of the 12V battery and body ground.

3. Most digital multimeters have the current range protected by a 10A fuse, so do not try to make the Prius READY while the meter is in line. Place the meter so it can be seen when the hatch is closed.

4. Close the hatch and all doors, lock the Prius, place the Smart fob more than 15 feet away from the car, and see what the current reading is after the ECUs settle down.

5. Gen 2 Prius will typically show ~0.015A to 0.02A current. I'd be interested to hear what your car's current reading is.

 

Patrick.

First, thanks for the advice about the wrong forum - I'm new here and didn't realise the significance - I just searched for "auxiliary battery problems" and followed the trail.

Next, thank you very much for your interest and the data about the expected battery drain. The car is presently at the dealers who seem unwilling to talk to me about the problem but as I see it at present, there are two possible outcomes:

1. The auxiliary battery has failed completely (something that has happened to me with a vehicle battery only once before, about 50 years ago) and Toyota will authorise a warranty replacement and no further action will be necessary or,

2. The battery will recharge OK and I will get the car back knowing that one night, the battery drained for no apparent reason - I am 100% certain there was no unusual load on the battery overnight - which suggests an intermittent fault which could repeat at random sometime in the future. This is my real worry.

In case 1, I will be reasonably happy (except for the Dealer's attitude) and I would prefer not to disconnect the battery to measure the quiescent current. In case 2, I will check the quiescent current and post my results. There is no way that a quiescent drain of 20mA would have much impact on a battery, even such a small one as the Prius auxiliary battery unless it is already close to failing.

Whatever the outcome, I will leave a note here as it may help someone else.

Overall, I have found it very difficult to get any sensible explanation of how the hybrid system operates (and being an engineer interested in all aspects of engineering technology, I would really like to understand the system. It is clever technology and understanding how something works always helps to understand it when things go wrong). The various dealers that I have dealt with seem to have no idea of how it works (although I now remember vaguely that when I bought the first Prius, the salesman made some comment about not letting the 12 volt battery get discharged by leaving the car unused for a long time, but if it did, being careful of how the car was started. At the time, it didn't mean much to me but after my recent researches, it is starting to make sense now.

Thanks again.

 

This might be of interest as an introduction:
http://www.ae.pwr.wroc.pl/filez/20110606092430_HEV_Toyota.pdf

If you want to dive deeper, Toyota has a subscription technical website: techinfo.toyota.com which contains repair manual info. In the past that website also contained the New Car Features Manual which provided "theory of operations". The NCF for the 2001 and 2004 model years were the most important as they provided lots of information on the Classic and 2G design. I don't know whether this practice was maintained for the G3 Prius.

 

Hi Ian. In regard to the Prius 12V system, the main thing that's different to a normal car is that the Prius only uses the little 12V battery to boot up it's electronics systems (ECUs etc), not to crank the engine. Once the electronics have booted then a DC to DC converter (powered from the main traction battery) supplies the 12V system, typically at about 13.8 to 14.0 volts.

Because the 12V battery doesn't have to crank the engine, it means they can use a smaller less powerful battery here. Unfortunately it also means that the early stages of a weak or dying battery will usually go undetected for a long time. Realistically, once a normal 12V battery has been fully drained like that they're never the same. Even if it's only 2.5 years old it probably won't have much life left in it now.

 

Patrick,

I now have the car back with the original battery. The Dealer charged the battery up and left it over two nights. They said they checked the quiescent drain current and it barely showed on their meter. They had no explanation as to why the aux discharged completely in about 18 hours but mentioned that in some UK spec vehicles it is possible to leave the "personal/interior" lights on when the vehicle is locked. I am certain that no light was on - I think I have used the personal light once, last winter, trying to find a street in an unfamiliar town, and it sure hasn't been on since then The bulbs are 6W so would take about 500mA. I'm not sure what the battery capacity is but it is physically pretty big - comparable to my BMW 1.8 diesel engined car - certainly not the "motor cycle" size battery I've seen mentioned. I think it unlikely that even if the light had been on that it would have completely flattened the aux battery. Incidentally, they did admit that replacement batteries are on back order in the UK and therefore not available for some time. I will do a few drain checks as you described, with and without various lights switched on. I will post the results here.

Thanks also for the links to the Hybrid descriptions - I had an idea about the mechanical aspects but knew very little about the electrics and electronics. I know a lot more now !

Thanks again

 

One of the issues here is that the Prius 12V charging system is not very aggressive, probably to to minimize gassing and water loss from the maintenance free battery. So I think that a lot of people who aren't doing a huge amount of driving are probably sitting at only about 70% charge on the 12V most of the time.

I'm not sure about your Gen3, but on the Gen2 prius it is very easy to accidentally leave a "footwell" light on by leaving one of the front doors ajar. These lights are fairly low in the front doors, so it's easy to not notice them after you've gotten out of the car. Also, they are *only* switched automatically (by door open), so there's not manual switch to override them. I guess you could drain around 10 amp-hrs if an interior light was on for 18 hours. And if your little battery was only 2/3 charged then that's probably enough to do the deed.

 

One thing is for certain, the reserve of the battery in the Prius is not a lot. 35 Amp Hours on the Gen II. That is not a lot. If a interior light was on for 18 hours, that would be enough to drag it down especially if the battery was not fully charged. As I understand it, the rating for the Gen II and the Gen III battery is the same. Therefore it really does not have a lot of reserve power.

 

Documenting my experience:
1. After a 1 month vacation, I came back and the battery was dead (Note: For what it's worth, I didn't disable the Smart Key system via the button under the steering wheel before I went on vacation).
2. The Fob didn't unlock the door. (red light on the fob still working though).
3. Inserted the manual and tried to turn it left and right, then right and left, etc.. It turned left and right but just maybe 5 degrees or something. The door wouldn't open. Tried a few times, but no success.
4. The next day a friend came by and I told him to turn it really hard as that's what somebody said on this forum. I ran upstairs to get something and when I came back the door was open. He said he just turned it left and then right and it easily opened.

Conclusion: He either turned it much harder than I did, or I loosened it up for him.

5. Epilogue: I was able to jump start my battery without any problems. Drove my car for about 30 minutes. Car was back to normal.

 

30 min is not enough time by a long shot. It would need the car to remain on for at least 18 hours to fully charge it in car. If your battery is recoverable, it will need to be put on a battery charger and fully charged.

Be prepared for further battery problems in your future, even if you do heed my advice and fully charge now.


PS, get some dry PTFE type spray lubricant and lubricate the key barrel in the door. Then use the metal key once a year to ensure it turns in both directions easily. Maintain as required.

 

I would take some WD40 and put it in the key opening with the straw that comes with the can and wet it down. Take your key and work it back and forward then wet it down again and it should free the lock up. It won't hurt anything.