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
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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
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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
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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:
Engine Block Disassemble
Remove the cylinder head locating (1, 2).
Remove the oil pressure switch (1).
Remove the knock sensor bolt (2) and the knock sensor (1).
Clean the thread.
Remove the oil flow check valve (1).
Remove the oil pressure rel ...
Input Speed Sensor Replacement
Removal Procedure
Remove the control solenoid valve and transmission
control module assembly. Refer to Control Solenoid
Valve and Transmission Control Module Assembly Replacement.
Remove the input speed sensor bolt (2) M6 x 23.
Unlock t ...
Range Selector Lever Cable Bracket Replacement
Removal Procedure
Set the park brake and chock the wheels.
Disconnect the range selector cable end (1) from the
range selector lever.
Disconnect the range selector cable (2) from the range
selector cable bracket.
Remove the transmission rang ...
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