Need Help: Doors won't lock/unlock

There's a known problem with Prius C door lock systems... Yours sounds a bit different, but first step is to do a search on google with priuschat in the key words and do some reading up on the subject.

 

can you describe 'working fine'?

 

otherwise, car is working fine?

 

i think you'll have to read the trouble codes. i hope vermin haven't been chewing wires

 

What diagnostic did you run on the 12 volt?

 

I agree, time to revisit that 12v test. Not everyone realizes that the difference between success and failure is only about one volt, when doing the simplest kind of open circuit testing.

A fresh, fully charged battery with no load (car completely off or battery disconnected) should read around 12.70V.

A 12.00 volt reading would suggest a battery that was significantly discharged or degraded.

How old is that battery? A 2012 would normally be working on its second battery by now, maybe even third.

 

Unfortunately the 2012 does not have jump points under the hood.
But wonder if you can hook up jumper cables to the batt (correct +/- on the terminals, to avoid messing things up)
and see if key fob works correctly then.

And as pointed out already, if 12v is the original, then likely the culprit.
Low/expired 12v starts giving funny dash lights and issues that can be easily remedied by changing it out.

 

I thought the 12v battery should read somewhere around 13.5 - 14 and change considering. If it is only reading 12, is that under a load? Have you disconnected the battery from the car (The negative terminal) and read the voltage across the terminals? Do you have a known, good 12v battery you can substitute in there or take a known, good, fully charged battery and a pair of jumper cables, attach it to the battery and see if your door locks operate. Even a lawn tractor battery should work for that.

 

hmmm, you have a dash that looks like that?

not sure the 2012 "c" has that internal dash 12v battery check.
When I had mine, I wasnt aware, although many things i could prob add to that list
Although a Gen3 (2012) would not have it either.

Do you know how to access the 12v battery?
If so, you could check to see it there is a date code on it, or see if it is oem.
Could also keep it accessible and then after say 12 hours could use
multimeter to check the resting voltage....but this cannot be done after drivers side door is opened.
Perhaps keeping the back door unlocked and then turning off interior lights
and then accessing it that way after the 12 hours of resting.

 

a dealer, or good hybrid shop has a tool called a code reader. it hooks up to the computer system at a port under the steering wheel.
when you get trouble lights, you get trouble codes. the codes relate to a service manual trouble shooting tree which leads to problem diagnosis and repair.

you can buy one for $25. on amazon (mini vci), but there is a learning curve, and you need a compatible laptop.
or there are some phone apps which work pretty well, but not quite as detailed, so don't always lead to a solution.
it all starts with a healthy 12v though, and that is tough to define when you get down around the level you're at.
the computers need proper voltage to give correct codes.

if you don't want to buy a new battery, you should at least try charging yours to see if it will hold at a higher voltage.

 

There are youtubes showing howto change the 12volt on a 2012 prius c.

Without knowing the codes that were set when the trouble started, none of us really knows much about what the problem is with the door locks. If you have an Auto Zone (auto parts store) near you and they are not too busy, they may plug there code reader into your car and show you what the codes are, sometimes even for no cost.

Write the code(s) down and and post them here and we can help you figure out what the problem(s) are.