So, did you ever actually figure out the issue with the coolant pump? I'm having the exact same problem, coolant pump stays on obviously when it's not supposed to and drains the 12V battery. It is definitely the coolant pump, if I unplug it and plug it back in right away it will start back up again, but if I wait 10-15 mins before plugging it back in it will stay off. I don't seem to have any issues with moisture in the connector. Pump itself going bad?