Troubleshooting HV ECU burnt connector (causes P0AFA, red triangle, 'replace hybrid battery' etc

Not dodgy at all.

 

What year is the battery from? If you haven't installed it, take a measurement of all the modules, make sure none of the modules have dead cells.

I would charge it before installing it, but that's just me

 

It is fine to charge it in the car. But it is not the same as slowly charging and discharging the pack with a grid charging system.

It's like filling up a bucket with a fire hose rather than a garden hose. It'll do the job but won't be as gentle.

 

Why keep the battery? It's 14 years old, only gets worse over time

 

This was a very helpful thread. I bought a 2007 Prius from the State Government Auction that I knew had battery issues. I replaced two blades in the battery pack and still had the triangle of death. Saw someone suggesting a burnt plug so I tore into the Battery ECU connector. Sure enough, corrosion had soldered the plug together and the act of prying them apart left three pins in the female portion of the plug. Ordered a used plug cable off of the net as well as an ECU and installed them this morning. No more triangle of death. Thanks for the insight and the photos above in this string as it all helped me. I have put some photos of what I took out of my Prius. I live in a high moisture content area, Western Washington, which I take from some of the comments on these plugs, contributes to the corrosion.

 

Do you remember if you had difficulty removing that cable from the ECU? I have a single code of P0ADC-226 with all the warning lights and I fear the ECU/cable may have fried themselves together.

A little background. Had a bad module showing up on Techstream/Dr Prius at position 13 with severely reduced ICE power and all lights glowing. This is a reconditioned battery at about 41K miles and 2 years old in sunny San Diego. Took it for a Dr Prius road test to test for battery life and on the way home I heard a loud pop from the battery area and the voltage from that module dropped from High 13s to 3s. I was able to limp home with electric ozone smelling smoke in the car..
No fire. The next morning i was still able to get the car to move to position it for the coming work.. so,, yes, it still started and without the smelly smoke. Opened up the traction battery and found one of the #13 modules had blown its top and the acid damaged the adjacent #12 module. So I replaced the 4 modules in 12 and 13 and strapped it into the car and the warning lights all came on but the car would not start...attempts to put in Drive went to neutral with the codes p0ae0 and p0afa. Yes, HV battery was bolted to chassis.. So I questioned my wiring installation, dug in and made sure all connectors were clean and tight and did not see anything suspicious then put the reassembled gear back into the car. Bolted it in place, like before and same no start but now with a new code of p0adc-226. The other codes vanished
During that 10 days or so it took me to order parts and get around to the fix, my 2 year old aux battery went from barely acceptable to failing at 11.8 V at rest and 10.4 when powered. I attempted to jump with truck and let it charge for 30 minutes which got it up to 13V powered an 12.1 V resting but car would still not start. After charging vehicle was removed from the circuit, the charge was slightly better, but still in failed battery territory. Have it on a trickle now. We'll see just how bad it is, but I am still concerned about being unable to remove the cable from the ECU. And because I can't remove the cable, I can't get at the bolts to remove the ECU. Hoping a new or newly charged auxiliary battery starts it up but I think there may be an ECU and cable that needs replacing. Wutya think?

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