SBM Functions
The body control module (SBM) is capable of accomplishing multiple body control functions. The systems that are directly connected to the SBM are controlled by the SBM's outputs. The SBM may control the outputs base upon the input information obtained from the sensors and switches that are directly connected to the SBM.
The SBM may borrow information from other systems on the serial data line. The SBM evaluates the information.
The SBM is capable of commanding other systems in order to control the functions that are not directly wired/controlled by the SBM. The SBM accomplishes this function by sending specific messages on the serial data line. The system capable of performing this function will respond to the message.
The Body Control Module
The SBM will enter a wake-up state if any of the following wake-up inputs are detected:
| • | Any activity on the serial data line |
| • | Any accessory function |
| • | The door handle switch (class 2 message from the DMM) |
| • | The door jamb switch (class 2 message from the DMM) |
| • | The door lock switch open or close (class 2 message from the DMM) |
| • | An RFA signal |
| • | An inadvertent power transition |
| • | The key in the ignition switch |
| • | The following components are ON: |
| - | Park lamps |
| - | Fog lamps |
| - | Headlamps |
| • | The SBM experiences a battery disconnect condition |
| • | The SBM experiences a reconnection condition |
| • | The ignition is turned to RUN |
The wake-up state is the state in which the body control module (SBM) is able to control/perform all of the system's functions. The sleep state is when the following conditions occur:
| • | The SBM stops active control |
| • | The SBM stops monitoring of the system functions |
| • | The SBM becomes idle again |
In order for the SBM to enter the wake-up state, the SBM detects certain wake-up conditions. The conditions are called wake-up inputs. The wake-up inputs cause the SBM to perform the following functions:
| • | Change from a sleep state to a wake-up state |
| • | Begin active control |
| • | Begin active monitoring |
The sleep condition indicates that the SBM , which is the power mode master of the vehicle, sent a message to the other systems on the serial data line in order to stop broadcasting the state of health message.
SBM Input/Output Information
The following components provide direct input to the SBM. Other systems may use the input information in order to carry out various functions.
SBM Inputs
Accessory: The accessory function provides the SBM with an input that may be configured as a high or low-assertion input.Auxiliary Chime: The auxiliary chime function provides the SBM with an interface that allows the external systems in order to chime an output of the SBM.
CRANK: The CRANK function provides an interface to the ignition switch in order to determine the ignition switch status.
Courtesy Lamp Switch: The courtesy lamp switch provides the driver the ability to request the illumination of the vehicle interior.
Ignition 0: The ignition 0 function provides an interface to the vehicle ignition switch in order to determine the ignition switch status.
Ignition 1: The ignition 1 function provides an interface to the vehicle ignition switch in order to determine the ignition switch status.
Seat Belt Switch: The seat belt switch provides an interface to the driver's seat belt switch that allows the SBM to determine when the driver seat belt switch is buckled.
Trunk Ajar Switch: The trunk ajar switch provides an interface that allows SBM to determine when the trunk lid is ajar.
Low Coolant Switch: The low coolant switch provides an interface to the coolant level switch in order to determine if the coolant level is low.
Washer Fluid Level Switch: The washer fluid level switch provides an interface to the windshield washer fluid level switch in order to determine if the fluid level is low.
Trunk Lid Release Switch: The trunk lid release switch provides an interface that allows the SBM to determine when the trunk lid release is requested.
Heated Seat Status: The heated seat status provides an interface in order to monitor if the heated seats are operating.
The SBM directly controls various outputs. Other systems may request that the SBM control the outputs for the appropriate functions.
SBM Outputs
Fog Lamp Enable: The fog lamp enable function controls the power to the fog lamps.Theater Dimming 1: The theater dimming 1 function controls certain interior lamps in the vehicle that dim.
Theater Dimming 2: The theater dimming 2 function controls certain interior lamps in the vehicle that dim.
Inadvertent Power: The inadvertent power provides an interface to the electrical loads that the inadvertent power circuit controls.
LCM Link: The LCM link provides an interface to the lamp control module that allows the SBM to determine the current ambient light operating mode.
RFA Link: The RFA link provides an interface in order to determine if the driver requests auxiliary lighting or if the key is in the ignition switch.
