Kids got water in spare tire well and now HV battery terminals are badly corroded

don't yell at the kids, more likely your getting leaks when it rains. search here for solutions. i can't advise on the connectors, but it might be worth examining the entire battery

 

Yea that didnt happen because of the kids, that is what happens over a long period of time. Yes you can do all that with it still in the car. Dont forget to remove the orange safety plug first.

Best if you just order a new set if nickel plated bus bars and nuts.


Posted via the PriusChat mobile app.

 

What codes were you getting? If none of them specifically point to weak modules, it might be worth a try (leaving the battery in the car and just cleaning the bus bars, bolts and nuts). Just be careful, even the with safety plug removed, it is possible to get a good jolt, if you touch the wrong thing.

 

The corrosion does look bad, however underneath the nuts it usually is perfectly clean. This is what matters most.
I suggest removing two nuts on one of the worst looking bus bars, and see what it looks like underneath. If nice and clean, just brush off the outer corrosion "in car", if desired, on the entire pack. A vacuum cleaner and stiff brush will make this job fast and easy.

 

Considering the amount of disassembly you've already performed, my opinion would be to remove the battery for the additional work. This way you can have it on a work table at a reasonable height for ease of work and viewing, along with reassembly. Not to mention, you won't be surrounded 360 degrees by metal while working on a component with significant electrical energy stored inside.

Safety first, my friend.

And if you are interested in really doing a good job? Just purchase a new wire frame #2 from Toyota to replace the wire harness/busbar assembly on the side of the battery which faces the seats. Trying to clean/reuse this harness can lead to many problems if you put a crack in one of the sensor leads. They are very susceptible to damage due to the corrosion you'll see on the wires and crimp area. The busbars shown in your photo (from the side of the battery facing the rear of the car) are easy to clean and reuse.

Torque all busbar fasteners to 48 INCH pounds (4 ft-pounds)

And..you may want to look at the bottom of the cubby hole where the 12v battery is located. Odds are very good you'll have a few inches of water in there also. Each of these areas has a rubber plug. I've removed the plugs (or drilled 1/8" holes) in those locations in my cars just so the water won't build up.

 

There are few threads on how water gets into a Gen 2 Prius. Many have hairline cracks near the hinges on the hatchback. Here is a long thread about it.

Water leak...into spare tire area etc | Page 6 | PriusChat

 

The socket you have in the photo does not match the plug in the previous photo. That 'nuked' plug and the socket it came out of are no good ===> The ecu is NFG and will need to be replaced. This is a VERY common occurrence on the Gen 2 cars. The harness/plug is called 'wire frame #2' and is available brand new from Toyota for <$60.