The body control module controls all electrical systems in your car. It is usually located mounted low near the driver's left knee.
Failure of this module causes battery drain when the vehicle is shut off. The little creature can drain four to six-amps in a short period of time. Signs of impending failure are inappropriate operation of electric windows, flashers or headlights.
Under many circumstances it is almost impossible to find a replacement, especdially for older cars.
Because the problem generally exists only when the car is shut off, disconnecting this unit (usually there is a harness plug) every time the car is shut down will enable you to operate the car until you find a replacement.