Chevrolet Sonic Repair Manual: Body Control System Description and Operation

Chevrolet Sonic Repair Manual / Electrical / Data and Communication Network / 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. ...

Fuses Junctions and Relays

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Other materials:

Parking Brake
To set the parking brake, hold the brake pedal down and pull up on the parking brake lever. If the ignition is on, the brake system warning light will come on. See Brake System Warning Light. To release the parking brake, hold the brake pedal down. Pull the parking brake lever up until you ...

Timing Belt Inspection
Special Tools EN-6340 Locking Tool EN-6628-A Locking Tool For equivalent regional tools, refer to Special Tools. Removal Procedure Remove the timing belt upper front cover. Refer to Timing Belt Upper Front Cover Removal. Set the crankshaft balancer in the ...

Engine Flywheel Replacement
Engine Flywheel Replacement Callout Component Name Preliminary Procedure Remove the clutch pressure and driven Plate . Refer to Clutch Pressure and Driven Plate Replacement. Special Tools EN-652 Flywheel Holder ...

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