smatthew
Active Member
disconnect the old 12V battery, then disconnect the HV harness underneath the rear passenger seat. The car will disconnect the HV and it's safe to replace the battery.View attachment 768092
Well, I jinxed it. Battery is original, so I guess 4 years isn't so bad given what people on here have been saying.
View attachment 768093
That a402 error seems new(ish). Either I got lucky and the battery fully died while the DC-DC was connected or Tesla is getting more proactive about checking while the car is in a powered state to try and reduce the number of people stranded.
Anyone know if I'll have trouble clearing these codes on my own if I replace the 12V while the DC-DC is on? Normally the processes is to wait for the car to sleep before swapping the battery, but I don't think that will ever happen with the a402 code present.
Then re-connect the HV harness, then reconnect the NEW 12V battery.
All should be right with the world.
Might take a drive cycle to remove the errors.