yes, i did search the archives first..... location: buffalo NY. temp 25 - 35 degrees. prius: 2004 model 9, 238k miles. just got these warning lights while driving 65 mph, no braking. shut the car off and back on; lights still on. drove home about 10-15 miles. checked battery voltage per priuschat instructions and it was 9.7. after checking voltage, lights all cleared. didnt look at inverter pump but could hear it. it was replaced under recall or warranty some time ago. is it safe to drive 100-150 miles (long commute) until i get replacement 12v battery? what else could be wrong with it (no i dont have error codes)? i am taking it in to toyota, but i like to be prepared. thanks for any advice.
The battery likely has a shorted cell and I would not advise to drive the vehicle any distance. I am surprised you can get into ready mode with the voltage that low, and the fact that both the power steering and brake power assistance both require a good 12 volt supply you could be putting your life and the life of others in danger. The car will loose trouble codes with a bad 12 volt battery, but the car will also generate all sorts of odd symptoms and messages. If you have a jump pack this could be pressed into service as your battery but if you do this I would advise disconnecting the OEM battery as this could discharge your jumper battery pack. John (Bitprius).
just spoke to a toyota service dept. before reading your reply; he said go ahead and drive it! so confused....
Obviously I cannot without testing be certain that you have one or more shorted cells in your battery. But the fact that you were driving the car at the time the lights came on "so the battery was being charged" strongly suggests this with a battery voltage of only 9.7 V immediately after driving. As a retired electrical engineer I cannot in all conscience in any way say that your car is completely safe to drive or will not let you down. I am not trying to scare you I am just being realistic. You may also have other problems, but the most likely thing is all this is caused by the 12 volt battery and once replaced things will be back to normal. A low battery stops the ECU's storing the fault codes, that is why many posts on here suggest disconnecting the battery to clear the codes a low battery does the same thing. No doubt someone else will post confirming what I have said. Hope this all makes sence. John (Britprius).
thanks, John. My hybrid battery is original, but the accessory battery was replaced about six yrs ago. So, it is due for replacement. I appreciate your safety concerns; I just have to get to work and see when the svc dept can fit me in. Factors outside of my control....
If you want to try to save yourself some money, take a little time and get a replacement 12 volt battery and swap the new one with the old one. If you are somewhat mechanically inclined you should find the job is simple and straight forward. I just changed ours, it took me 1.5 hours to do it on my own. I used two wrenches - both of which were 10MM and 12MM, two 3/8" drive sockets - both of which were 10MM and 12MM, a few extensions along with a ratchet (3/8" drive), a flat blade screwdriver, and a small hammer. If you do change the battery, make sure you disconnect the negative side first and then reconnect it last. It is pretty obvious that your battery is bad since it is a LOT less than 12.6 volts (100% charge) and that it is six years old. Good luck to you. Ron
update: I started the car this am, got to the end of driveway, and lights came back on. called svc when they opened and they told me to come right in. they found codes for the battery (it had a dead cell) and one for the rt rear wheel sensor. installed a new battery for $240. the extra money was worth NOT trying to do it myself! Late to work, but peace of mind and (knock on wood) no dash lights. thanks for your help!
Glad you got it sorted for not to much money. As you can guess I had a very strong feeling from the voltage from the battery directly after use that a cell had shorted. John (Britprius).
$240 is a good price for battery with install. Average price for the battery alone is $200 plus, so you got off pretty good imo. Glad to hear you got your problem solved. Good luck to you. Ron
thanks to you both! i especially like the fact that i wasnt trying to figure out how to install it in winter weather! update number 2 - the lights came back on this evening; svc guy thinks its the rear wheel sensor causing lights to come on. will make an appointment for that; if i keep spending 2-300 dollars a month, time to trade up to a 2008!
Try going to one of the auto parts stores or shops that will read codes for free & let us know what they find.
Makes sense so far, then you wrote: Sorry, but I am confused. You mentioned rt rear wheel sensor in post #8 this string, and then you again mention a rear wheel sensor in post #11. Did you decline the sensor when you had the battery put in, or have they replaced one and now they think another sensor is bad? If you can get the DTC codes and post them, it might help to clarify things. I know the feeling about repair cost's on car's. Everytime I do work on ours, I think along the lines of getting something newer. Then I stop and think some more. I end up saying "This one is paid for, I don't want to start making payments again." Hopefully lady luck will shine on you soon. Ron
The to me bad side of the OP's problems was that the dealer told the OP that it was ok to drive the car on a 150 mile journey with the battery in that condition. This shows a complete lack of understanding of how the Prius works. With a shorted cell the other cells would be in permanent over charged state making it likely that another cell would go down this could have given rise to a dangerous shutdown possibly without power steering and power assistance to the brakes, as both systems work on 12 volts. John (Britprius).
Ron, the dealer did not replace the rear wheel sensor at the time of battery replacement. That was just an emergency visit w/o apptmt to make sure battery was working. I will return next week for the other. He said it could be one of a couple different things and they would need the car longer.
John, just to be clear, the dealer that told me it was ok to drive with bad battery was not my dealer - just some random toyota dealer with Sunday hours. My dealer had me bring it in immediately when I called!
I've been kind of abbreviating my thoughts because, apparently, priuschat is not android friendly. having a tough time typing messages here! It won't let me do separate paragraphs....My svc guy said I wouldn't have abs or vsc until the sensor (or the wiring harness or whatever was causing the code was fixed, but said it was ok to drive as long as I was aware of it. No mention of power steering, although he said the mechanical brakes would work fine. I plan to bring it in next Saturday so I dont miss more work. The warning lights are intermittent, now. It appears they are only coming on when I lose traction. Then they go off on their own a little while later....... I hope this is my last issue for a while; I really want to get 300k on this one and get the opportunity for a reasonably priced used seaglass pearl package five with AT option
The wheel sensor will not affect the steering it is the 12 v battery that I was concerned about as that affects just about everything on the car. Glad it was not your own dealer that said just drive it.
