This cable is kaput. The blue corrosion runs on the wire strands clear to the other end at the safety plug.
The title of this thread is "I find the cause of my problem...finally!". Can you please state what problem you are trying to fix on your Prius? Did you replace the cable, and did that fix the problem? Edit: I wanted to add additional question . Did you measure the resistance of the corroded cable?
The hybrid battery keeps getting warm and won't cool back down. The non-corroded wire measured 0.1 ohms, the corroded wire measured 0.2 ohms. If my electrical math is correct,the amount of current that wire could handle would be halved, and resistance means heat, and there's a lot of amps on that wire I'd imagine.
That's certainly part of the problem in your reconditioned hybrid battery. Better than the last blower motor "fix" (or should we say fixation?). Proof is in the pudding. I am betting more corrosion exists along with a few weak modules.