The body control module in a car is generally located underneath the car's center console or behind the glove compartment. If the body control module is not here, the car's owner's manual provides the location.
The body control module is the control center for the car's various electrical components. The BCM and the human body's central nervous system act in the same manner. The BCM controls electronic windows, door locks and auto lights. If the BCM is not operating correctly, these may not function properly or function at all. If there are problems with these components, replacing the BCM should correct the issues.