BCM Overview
The main features of the body control module (BCM) are:
| • | The BCM is the gateway between class 2 serial data circuit and
high speed GMLAN serial data circuit. |
| • | The BCM controls multiple functions. |
| • | The BCM is the power mode master. |
Gateway
The body control module (BCM) communicates functionally on both class 2
and high speed GMLAN serial data buses. The BCM is the gateway between the buses and
transfers serial data messages from one subnet to another. Physical communication
of the BCM with the scan tool is through class 2 serial data circuit.
BCM Functions
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 inputs can be:
| • | Sensors and switches that are directly connected to the BCM |
| • | Class 2 serial data messages received from other vehicle systems
connected to the class 2 serial data link |
| • | GMLAN serial data messages received from other vehicles systems connected
to the high speed GMLAN serial data link |
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 or high speed GMLAN serial data link. The system capable of performing
the required function will respond to the BCM messages.
Some of the other system functions that BCM controls or contributes to are:
Power Mode
The BCM is the power mode master (PMM). Refer to
Power Mode Description and Operation
for more information.
