Problems after rain

What does this mean?

You could have a low 12V since not enough 12V power gives error codes.

Or you could have rodents snacking on your wires while sheltering from the rain.

Aside from that, you'll want to address the leak that's letting water into the 12V battery area.

 

There are certain specific trouble codes that are associated with a (n extremely) low 12 volt battery. You can end up getting C1241 or some C230x codes, for example. The C230x codes will light the master warning light (the triangle).

So, you can learn a good deal about the likelihood of a 12 volt battery issue by finding out what trouble codes you have, and even more by looking at the freeze frames for those codes to see what voltages were recorded.

Even those codes are not caused exclusively by 12 volt battery issues, because they are about the power as received at some other location in the car, so wiring and connections on that path are also a factor. So if you have such codes, it makes sense to quickly check the battery condition, then proceed with a meter to checking the wiring and connections if a simple battery issue wasn't found.

Finding rodent damage is a similar process. You can use a multimeter and the wiring diagram (more info) to locate connections before and after an open circuit, and home in on it that way, until eventually you've given yourself a narrow section of wiring that you have to physically look at. A short is a bit harder because your meter can't find a before and after; it will measure as shorted from either end. But you can at least narrow it down to one section, and then go looking for tooth marks.

 

@ChapmanF had a great answer in post #4. He's way better at what codes indicate what. I would have just invested a minute or two in putting my meter on the 12V battery test points under the hood and gone from there. If it was low, fix that. If it was over 12V, then I'd be investigating those codes and maybe chasing the wiring possibilities as he described.

The voltages on your traction battery don't look bad to me. The two mili-ohm range in resistance would seem to indicate that it's beginning to show its age.

 

I agree with Jerry that the traction battery voltages don't look unreasonable.

As for the codes and the 12 volt battery, well, if you have a multimeter and a scan tool it's about equally easy to grab either one first. My habit is to grab the scan tool first, but that's me.

With my multimeter, I will find out what the battery voltage is now.

With my scan tool, I will find out what the battery voltage is now, what it was at the time of any freeze frame, what the ECU thought of the battery voltage at the time, and anything else the ECU feels like telling me about. Not a bad payoff for connecting one plug, and some mouse clicks.

Have you got any measurements of your 12 volt battery voltage to share?

 

You're pretty much on track there, except there's no alternator; the power source in a Prius is called the 'converter', and yes, this shows the converter is working.

Probably a red herring. 12.05 won't win you any 12 volt state-of-charge awards, and you wouldn't be wrong to recharge it or replace it if you want, but it shouldn't distract you from troubleshooting your car issues either. For a sense of perspective, your Gen 2 repair manual will say "if the voltage is below 11 volts, recharge or replace the battery before proceeding." It's generally in the 9 to 10 volt range where the ECUs actually begin logging "hey, did you know the voltage is a bit low?" codes.

You're right to ask; there is no "hybrid battery indicator". The big triangle is the "master warning light", and the little car-guillotine icon is the "hybrid vehicle system warning". They both have around 200 reasons for coming on. You find out by reading the trouble codes.

The lights come on because trouble codes have been logged; you get the rest of the information by getting the codes.

The master warning light is lit when the Hybrid Vehicle ECU has codes. The ((!)) and VSC lights come when the skid ECU has codes (even if it only has codes like C1259 or C1310, which just mean "I'm relaying a message that the HV ECU has codes"). The airbag light comes on when the airbag system has codes.

The repair manual (more info) has explanations and troubleshooting steps for all of the codes.

 

Most of the codes I do not have memorized, because there are no extra points for making a memory test out of it. Full credit is given for just going to the repair manual and looking them up, and following the troubleshooting steps that are given there.

C1310 is one that I do know by heart, because it comes up so often. That one is just the skid ECU saying "hey, I heard the HV ECU has some codes". So when you see that one, you look at the other codes you have to see if they include any from the HV ECU. In your case, that's the P3107. (If you didn't have any HV ECU codes but you had a C1310, you would know to set aside the code scanner you'd been using and get one able to show the HV ECU codes that you know have to be there.)

Also, C1310 in a Prius has nothing, absolutely nothing, to do with an "active booster solenoid". All C1 codes form a group that's officially "manufacturer defined" and can mean completely different things between makes of car, sometimes even models of the same make. Any time you see "active booster solenoid" listed with C1310 you are seeing a mistaken match for what that code means in some other, completely different car.

So you have the P3107, and you know that's why you have the C1310. Therefore you know the HV ECU is unable to communicate with the airbag ECU. if you have a scanner that can show you the 3-digit "INF" subcodes, those will tell you a little more about what sort of cause you are looking for.

You also have the B1000, which is the airbag ECU itself reporting a problem passing its self-test. That seems pretty clearly related to the P3107 (and the C1310).

The B1271 is a little something different thrown in, a communication problem between the combination meter and the gateway ECU. The Gen 2 has a combination of networks, including CAN (the industry standard that was coming into its own at the time) and Toyota's older "BEAN" bus. There's a gateway ECU that relays communications between the two, and the combination meter is one of the things on the older BEAN, as you see in the diagram in the "multiplex communication" section of the repair manual.

That doesn't seem directly related to the other codes concerning the airbag ECU, other than a general theme of communication issues. The airbag ECU doesn't seem to live on either the CAN or the BEAN directly, if I'm reading the wiring diagram right, but has its own direct connections of some sort, both to the HV ECU and to the combination meter.

If it were my car, I would be spreading out the repair manual and the wiring diagram at the corresponding pages, grabbing my multimeter, and starting at the front of the troubleshooting steps in the manual.