I have issue with my battery being drained. I have no codes pop up. I purchased a new battery and it still drained overnight. Both batteries are at 12.7 when charged, then it jumps to 14.6 when car is on. When I reverse, it kicks in. When I put it in drive, it defaults to 3rd gear. BCM already ruled out. When I turn the lights on it's very weak, also, when I put load on alternator it shows load even when the battery is weak. I'm trying to get to the bottom of this because with no codes I'm lost and don't want to spend a fortune at Mazda just for a diagnostic (it's 145$).