Hybrid System Warning - Help Troubleshooting

Good day to you all - long time lurker and Gen 3 owner. I have two 2010s.

Issue: Gen3 2010 with 180k had a dead 12v. When jumped got a hybrid system system warning.
Replaced 12v with OEM from dealer. Started right up and then later that day warning appeared while driving.
The next day the battery was dead, but readily took a jump and has been fine since even though it is not driven much.

*disclaimer* I do not understand electronics very much, so I am only putting our raw info without really being able to interpret much of it. I have a basic Klein multimeter. That's why I'm here asking for guidance.

First, I looked for parasitic draw by testing the fuse connections when car off and found:
1) ABS main no. 2 was drawing 0.3 mV or 30mA
2)P/I 2 relay (40A) was drawing 1.27V
3) 12v battery had 0.17A resting draw when touching negative terminal to ground.

I have had no more dead batter issues and the hybrid warning has been intermittent since then.

I pulled codes with Car scanner and have seen a series of peculiar DTCs as well as a couple equipment specific codes.

Also, once while driving on the highway, the car went into failsafe after warning appeared and went away with a restart. I drove about 100 miles after that with no problem. When I started it again later that day after the trip, warning came back. Typically this is what I am seeing: starts up fine, drives fine, and then when I start it up again later that day I get a code, but no detectable performance issues.


Here are the various revolving DTCs I have been getting during this timeframe:
P2532: lgnition switch, ON position - circuit high (had this one twice)
I tested according to Chilton at the IG2 ground short test: got 6.88v to ground on IG2 at the Power Management Control ECU wire harness pins behind the glove box. Then removed IG2 relay and got 5.8V. Then a P lock malfunction so I'm trying to resolve that now. At same time, tested 12v battery and got 12.5V when positive was unplugged.

P3107: Air bag ECU or communication circuit fault; airbag ECU communication circuit malfunction

P261B: coolant pump motor B - control circuit range/performance (I only got this once, but I bought the replacement just in case given age of car, and when driving car scanner will not show any RPM from engine water pump even when temp exceeds 210-220 (I did not push it beyond this). It also may be a circuit issue not showing the actual pump RPM given all these communication issues.

P0A0F: Hybrid drive system - engine failed to start


U0100: Data bus, ECM A - no communication (every time)
U0129: Data bus, brake system control module - no communication (every time)
U0293: lost communication with hybrid powertrain control module (every time)
U0164: Data bus, AC control module - no communication
U0155: Data bus, instrumentation control module - no communication
U0151: data bus, supplemental restraint system (SRS) control module - no communication

B2282: power source control (twice)
B2312 (electric window rear left and rear right doors)
B1423: open pressure sensor circuit / abnormal refrigerant pressure (progr, rx3)

These ABS codes have been constant:

ABS Control Unit 2:
C0210: rear wheel speed sensor malfunction (cald, cam, del.)
C1238: sensor circuit (MR) speed sensor rotor / right rear (cel.)
C1241: IG power source circuit (MR, cel.)

Here are some concerns I have:
Rodents are a possibility and have been in cabin air filter in the past, but not much this year if at all. I cannot see chewed wires, but imagine that would not cause intermittent issues.

Discovered that the driver side plastic fender liner has been missing unnoticed. I am in New England with salt, sand, wetness and wonder if this is due to corrosion or dirty contacts around wires new engine bay fuse box. Any advise on how to safely clean this and look for issues would be appreciated as I wait for a new fender liner to arrive.

As noted above, when driving with the car scanner app running I do not see any water pump RPM, but not sure this is a genuine reading given the electrical issues present.

Any troubleshooting guidance would be appreciated. As I said, I have an identical Prius if swapping the power management ECU as a test could be done, or the IG2 relay or anything else within reason.

Thanks! Aren't these cars fun? Incredibly reliable until this instance.

 

I will first try out my OBD reader on my (I think) fully functioning Gen 3 to see if it if reads the water pump RPMs. Then I will need to research software that can command the pump on. I'll take any recommendations on software - thanks!

 

I believe I did this overnight when it died immediately after installing. I should try it again. So much of what I read about with these issues seem to come back to low charge of the 12V. However, I am a bit concerned by my parasitic draw test result and the test result on the IG2 ECM pins showing that it was drawing voltage when off. Wondering if there is an underlying issue, but have no idea how to sort out troubleshooting. The Chilton manual just says to start replacing the ECM, the wiring harness, and then the relay (last LOL).

 

UPDATE:

Fully charged the battery and struggled to get the engine to start, but once I got it in maintenance mode I was able to drive. The same communication codes are being shown, and the IG2 tests still show 4.5 v from the ECU harness IG2 pin to ground with the IG2 relay removed, so I don’t think it is the relay.

I also confirmed that the Car Scanner app doesn’t have the ability to read water pump RPM, so not sure the water pump is broken. HOWEVER, after driving a little bit, I opened the hood and heard that the water pump was running long after the car stopped. I made sure it was the pump by yanking the w/p relay.

Any ideas what could be causing these communication errors? Could it be wire damage by rodents? Could it be debris on wiring due to the missing fender liner? I need help and I know the stealership won’t do the hard tests. They’ll just start swapping expensive parts until they can’t solve it.