So I was pulling my hair out until I found this thread... After leasing my 2014 Leaf for 3 years, around Apr 3 I bought it out at a nice discount and had them throw in the 3G module upgrade. That's when my problems started
12V battery died about 2 weeks later. Took it to Advance Auto, they said the battery looks to have a failing cell. Bought a replacement and figured no big deal - 3 years on a factory battery is probably fine.
A few weeks later the new battery was dead in the morning. Took it to the dealer with 2k left on the 36k warranty. They kept it for a week - no problems found.
Started reading this forum talking about charging profiles for the 12V battery. So I tried to stop leaving the L2 charger plugged in for too long, and started checking the 12V levels some evenings, bought a desulphating trickle charger and started plugging it in every few days.
Tried to baby the 12V battery for the next few months. Things were generally good though I started trusting the Leaf less and made sure my ICE vehicles were maintained and ready to go as backups each morning
Nissan Connect started being unreliable a couple weeks ago and stopped responding entirely last week. A day or so later the 12V battery died again and the dreaded yellow ! car showed up on the dash. Ordered and received and LeLINK ODBII yesterday and downloaded LeafSpy last night. Read and copied the 10 or so DTC codes and started searching this forum again.
Found and read way too much of this thread last night. This morning found the Audio fuse (20A in the left middle of the fusebox to the left of the 12V battery). By the time I drove to the office the Nissan Connect was working again.
Skip to here if you are in a hurry:
Long story to ask one question: Does anyone know which one of these two theses is true of how this failure happens?
1) Does the TCM pull more than the 2G module during normal operation, draining the 12V battery and locking up the TCM module?
2) Does some failure in the Nissan Connect connection cause the TCM to lock up, and at that point it starts draining the hell out of the 12V battery until it fails and the Yellow!Car appears?
Basically I want to know if 1) I need to keep monitoring the battery and make sure it stays topped up, or 2) just reset the TCM (via the audio fuse) as soon as it doesn't respond, in order to prevent the 12V battery from draining?