You're getting lower and lower voltage as you get further from the battery. It does sound like cables. The cable runs from positive battery to the side of the underhood fuse block, then to the starter, then to the alternator.

Your nearest auto parts store should perform a free battery load test and charging system test. However 1 time I went, they said my battery was discharged too far, they could not test the charging system.

 

"mechanics" always advise to replace computers because they are scared of them. If a computer module is even mentioned in a DTC description it jumps to first thing. They rarely are to blame but he connectors are so when it solves the problem they declare victory, with your wallet contents in hand.

It is easy and cheap enough to replace those 2 cables since you are past the expensive parts.

 

I just did some service work in the BlackSwan, I started it up and the device traction and abs and the CEL came on.

was it the brakes, should not be, I didn’t touch the brakes, was it the engine control module, nope did not touch that.

Oh, found it I forgot to reconnect the MAF sensor, the CEL was P0113, related to intake air temperature, which cannot be monitored if the sensor isn’t pulled in.

I cleared the code , reconnected the MAF , all the messages and lights went out. Car runs great, no parts required.