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:
Emblem/Nameplate Replacement
Caution: Refer to Exterior Trim Emblem Removal Caution.
The part and vehicle surface should be 21?°C (70?°F) prior to installation.
The vehicle should remain inside in a temperature range of 21?°C (70?°F) for
1 hour after assembly to allow the adhesive to develop sufficient bo ...
Full-Cut Method Description
Note:
If corrosion of the pinch-weld flange is present, or if sheet metal
repairs or replacements are required, refinish the pinch-weld flange in
order to present a clean, primer-only surface.
If paint repairs are required, mask the flange bonding area, prior to
applying th ...
Tire-to-Wheel Match-Mounting (Vectoring)
Note: After remounting a tire to a wheel or after replacing a tire
and/or a wheel, remeasure the tire and wheel assembly runout in order to verify
that the amount of runout has been reduced and brought to within tolerances.
Ensure that the tire and wheel assembly is properly balanced ...
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