New to forum - what problems can the 12v battery cause?

welcome! sometimes they are, and sometimes they're not. best to start with a voltage check.

 

Welcome to PriusChat! You might find "search" to be helpful - there are many threads hereabouts concerning problems associated with a failing 12V Aux-battery and how to deal with them. Good luck! - Wil

 

The most important (costly problem) is that each time you jump start a Prius, you risk a $4000 repair if you reverse the cables, even for a second.

The 12 volt battery powers the Computers that check to see if the car is operating correctly, when it can't power them any more you will get spurious error messages that have nothing to do with real problems. This can lead you astray.

And finally, it may not choose to start the car at all.

My opinion, (and it is just an opinion) is that any time after 4 years, if you think the 12 volt battery is causing you trouble, replace the 12 volt battery.

(The 2016 may have a less troublesome battery, we should know by 2020)

 

For unusual electronic problems on the Prius, the 12V is a good first place to look as it's often the cause and is easy to check. I would get a voltmeter and read the voltage car off, voltage car in ACC ON after 30 seconds, and car in Ready. If either of the first two is below 12.2 or so, it points to a battery issue. If the last one is below 13.5, it points to an inverter issue. If you can't or don't want to do this yourself, take the car to an Autozone or other car parts store that will do a battery test for free.

Every Prius I've read about on these forums seems to behave differently when the battery gets low. The behavior you're experiencing certainly could be the battery.

 

It could also be the Combination Meter (CM) starting to fail, certainly the car not turning off is a symptom of a failing CM.

 

Agreed, this is the next place I'd look after checking the battery.

 

Mine has this issue. After replacing my battery it still existed.

You can read the below info and decide for yourself if your competent enough to take on this task. I believe the temporary remedy is simple for me but not for everyone.

Do at your own risk. If you can safely take out the 12 volt battery on typical cars you should be able to handle this. If not seek assistance.

For this temp fix it will involve some minor disassembly and reassembly. The battery will not need removed in this procedure if the battery has been checked out as good prior.

1. Engage your e-brake.

2. I usually release my foot from brake and hold down the power button until engine turns off. Much like a reset button on computer.

3. Unlock car doors with unlock button on drivers door. This will also unlock hatch.

4. Exit your vehicle with your keys.

5. Open hatch then remove the triangle cover plate covering your 12 volt battery which is located in the passenger rear corner of the trunk area. Think passenger floor area immediately in front of rear passenger tail light.

6. Look on the top of battery for a plate with a low voltage wire attached to a white plug. This plug locks into terminal mounted on top of battery.

7. There is a tab on the bottom side of the plug. I use my index finger to locate it. Push up on this plug while grasping the plug with other fingers & thumb. Slight wiggling and pulling on the white plug (not wire) will be required.

Avoid use of tools that can damage or short out the cable.

8. After some reasonable effort it will eventually slide out and you will quickly notice the hatch and interior lights will turn off.

9. Leave the white plug disconnected about 20 seconds and then plug back in the white connection. Your interior lights should come vack back on.

10. After that go up and sit in drivers seat. Press brake and then power and it should turn on and off like normal.


11. If it worked you can put your car back together and go on your now much merrier way.



For me it Works until next time. I believe the real fix will be the combination meter repair. From my experience expect it to progress quickly.


This method also happens to be the only way to remove the keyfob from the slot in the dash during these circumstances.

 

contact steve at autobeyours.com for swap price.