The body control module (BCM) performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM control inputs can be:

The BCM is also capable of controlling other vehicle systems that are not directly wired to the BCM. The BCM does this by sending specific messages on the class 2 serial data link. The control module capable of performing the required function will respond to the BCM message.

The BCM functions include the following:

The BCM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.

The power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharge condition. This is accomplished by using a high accuracy battery voltage reading as an indicator of battery discharge rate. The following 6 levels of load management will execute in the load management control algorithm when there is a high discharge condition:

1. The first action requests a vehicle idle speed increase to the powertrain control module (PCM) in order to raise alternator output.
2. The second action requests a greater vehicle idle speed increase to the PCM in order to raise alternator output.
3. The third action begins to shed vehicle loads in an attempt to remedy the heavy discharge condition.
4. The fourth action requests another vehicle idle speed increase to the PCM in order to raise further the alternator output.
5. The fifth action begins to shed further vehicle loads in an attempt to remedy the heavy discharge condition.
6. If the above five corrective actions fail, the sixth action of power management further sheds loads in a final attempt to remedy the high discharge condition.

Loads subject to reduction include the following:

Each load management function, either idle boost or load-shed, is discrete. No two functions are implemented at the same time. During each load management function, the PMM checks the battery temperature, battery voltage and amp-hour calculations and determines if the PMM should implement a different power management function.