Chevrolet Sonic Repair Manual: Body Control System Description and Operation
The body control system consists of the body control module (BCM), communications, and various input and outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has discrete input and output terminals to control the vehicle's body functions. The BCM is wired to the high speed GMLAN serial data bus, low speed GMLAN serial data bus and Multiple LIN buses and acts as a gateway between them.
- Power Mode Master
-
This vehicle body control module (BCM) functions as the power mode master (PMM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determining the power mode that will be sent over the serial data circuits to the other modules that need this information; the PMM will activate relays and other direct outputs of the PMM as needed. Refer to Power Mode Description and Operation for a complete description of power mode functions.
- Gateway
-
The body control module (BCM) in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the GMLAN high speed bus and the GMLAN low speed bus for communication between the various modules. The gateway will interact with each network according to that network's transmission protocol.
All communication between the BCM and a scan tool is on the high speed GMLAN serial data circuits. A lost communication DTC typically is set in modules other than the module with a communication failure.
- Body Control
-
The various body control module (BCM) input and output circuits are illustrated in the corresponding functional areas on the BCM electrical schematics. Refer to the Body Control System Schematics for more detailed information.
Body Control Module Replacement
Body Control Module Replacement
Callout
Component Name
Preliminary Procedure
Remove the instrument panel lower trim pad cover. ...
Other materials:
Tire Terminology and Definitions
Air Pressure: The amount of air inside the tire pressing outward on each square
inch of the tire. Air pressure is expressed in kPa (kilopascal) or psi (pounds per
square inch).
Accessory Weight: The combined weight of optional accessories. Some examples
of optional accessories are automatic t ...
Drum Brake Hardware Inspection
Warning: Refer to Brake Dust Warning.
Visually inspect the drum brake upper return spring (1) for the following
conditions:
Excessive corrosion
Excessive stretching
Broken
Missing
If any of the conditions listed were found, the drum brake upper return sp ...
Ignition and Start Switch Housing Replacement
Ignition and Start Switch Housing Replacement
Callout
Component Name
Preliminary Procedures
Remove the theft deterrent module. Refer to Theft Deterrent Module
Replacement.
Remove the turn signal switch bracket. Refer to T ...
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