Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
System Operation: BCM
The BCM controls various systems by monitoring inputs from switches, sensors and messages sent from other modules on the HS-CAN1 and from the GWM. Based on the inputs received, the BCM activates outputs. For example, the BCM monitors the headlamp switch position. Based on this input, the BCM may provide voltage to the exterior lamps. For a list of BCM controlled functions, Refer to: Module Controlled Functions - Overview .
Battery Saver
The battery saver feature is used to conserve battery voltage. The BCM provides automatic shut-off of the interior lamps after a time-out period when the ignition is off. Refer to: Interior Lighting - System Operation and Component Description .
Battery Load Shed
The BCM monitors the battery state of charge in order to save the remaining battery charge when necessary. For more information,
Post Crash Alert Function
The post crash alert is a function controlled by the BCM. If the RCM determines an impact of enough severity has occurred (the airbags may or may not be deployed), the post crash alert function activates.
The post crash alert function:
- sounds the horn.
- turns on the hazard lights.
- turns on the interior lights.
- unlocks the doors.
The post crash alert function can be turned off by:
- pressing the hazard flasher lamp switch (which may need to be pressed twice).
- pressing the transmitter unlock button.
- pressing the RKE transmitter PANIC button.
- cycling the ignition switch (RUN-OFF-RUN-OFF-RUN).
- opening the driver door.
Factory-Transport Mode
During vehicle build, some modules (such as the IPC and the BCM) are set to factory mode. When the vehicle build is complete, the vehicle is set to transport mode.
Transport mode is used to reduce the drain on the battery during longer periods when the vehicle is not used. Various system functions can be altered or disabled when in the transport mode. While in transport mode, the IPC displays TRANSPORT MODE in the message center. Transport mode can be disabled and placed into normal operation mode. Refer to: Transport Mode Deactivation .
Car Configuration Parameters
The parameters are set in the BCM. The parameters are also set in the IPC as backup data for service, in case online As-Built data is not available. For more information, Refer to: Module Configuration - System Operation and Component Description .
Steering Column Lock Module
The steering column lock module locks and unlocks the steering column based on commands received from the BCM. For more information, Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description .
When the steering column lock module is replaced, the BCM must be configured/trained to the new steering column lock module for the steering column lock module to operate correctly. Refer to: Anti-Theft Key Programming - Scan Tool .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.