Body Control Modules: Operation

Battery rundown protection (or battery guard) feature provides protection from excessive battery drain caused by high current loads that are accidentally left on. When ignition is turned off, a time-out period is started. If odometer reads less than 15 miles, time-out period will last for 3 minutes. If odometer reads more than 15 miles, time-out period will last for 20 minutes. When time-out expires, inadvertent power output is turned off.

Each time ignition switch is turned from ACC to RUN position, BCM controls an instrument cluster bulb check for a calibrated amount of time. During this bulb check, instrument cluster will perform a WOW (gauge needle sweep from low to high to low positions) check.

When BCM activates an indicator in the instrument cluster, it may also produce a chime. The following chimes are provided: key-in-ignition, headlights on, unfastened seat belt, turn signal on, parking brake warning, door ajar warning and check gauges.