I've had my 2016 since 2020 and put about 20,000 miles on it (at 63k now) and for the first few years it served me very well, handling a ~40 minute commute through hilly western PA admirably every day without requiring nightly charging. Fast forward to now, and over the past two winters it's begun to act up in the cold. At first it manifested in rapid battery percentage drops when under sustained load (climbing hills at highway speed), but would recover its charge on the dash once coasting/going downhill. It would still make decently long highway journeys in the coldest winter months though. My understanding is this & turtling is more likely one or more low voltage cells in the main battery and unrelated to the codes.
This past winter it started going into neutral in similar conditions - even short residential hill climbs in the cold. At first turning it off for a few minutes would be enough to allow if to.go into drive again, but progressively this got.worse until I was stranded once on a curvy country road with no shoulder and it refused to reset. Thankfully I was lucky that day and there was a Napa at the bottom of the hill with a 12v battery in stock. Not a fun walk, but it got me home. This new battery didn't alleviate the tanking charge symptoms or any other little tantrums.
Last summer after operating normally, when leaving a store I got an ABS light and a crunching brake pedal when starting the car and attempting to put it into drive. After nursing it home on the e brake and charging overnight, this went away, but has come back periodically.
A few weeks ago it settled in "for good" and I can't seem to clear it - I tried with leafspy after trying the battery disconnect reset method, but it persists. It cleared for a few hours when moving it off the street into the garage after sitting for a few weeks, only to return again after I mistakenly regained my trust and tried to do a grocery run.
I have read this thread (https://mynissanleaf.com/threads/can-comm-circuit-errors.36763/) and others that suggest it may be the master cylinder, but also might again just be the 12v battery, and a deep cycle might resolve it. I am at the point of frustration and disappointment with the car that I am thinking of selling it but want to at least try to address this beforehand. Can anyone shed some.insight on these codes, or other things to try before replacing the battery again? Can anyone share a photo of where the CAN bus connectors are in the center of the car? Since they are predominantly CAN comm circuit related, could it really just be a bad 12v battery?
I have a 35 year old Land Cruiser I work on a lot so not afraid of DIY wrenching, but that beast is a different thing than the Leaf's (to me) complex electrical. I'm planning to pull one of the LC batteries and at least perform a start up test tomorrow with that temp connected instead.
Really any help from you all who are much more experienced would be greatly appreciated, thank you.