You should clear the 12v light if you disconnect the fireman's loop and the battery for 15 minutes.My 12v has been working fine again. I replaced the 12v battery sensor on the negative cable. And found a loose positive battery cable. Now the 12v light still comes back every 2-3 days even after i hard reset with wheel config. If the car has a fault due too a loose cable or something will it keep throwing the 12v error? Is there some kind of memory of the fault with that specific battery?