any now what the problem is vt electrical confusion

[craig.austin]

my vt is acting strange my headlights come on when i start the motor and when this happens it drains the battery and so when i turn the car off it wont turn over to start but it is intermittent very strange first my air con fan wouldn't turn off then my rear heater wouldn't turn off now this i replaced alternator and battery and relays any more suggestions pls

[Burnout124]

bcm or ecu ?