System Description

BCM (BODY CONTROL MODULE)


System Description

BCM (Body Control Module) controls the operation of various electrical units installed on the vehicle.

BCM FUNCTION
BCM has combination switch reading function for reading the operation of combination switches (light, wiper, washer, turn signal) in addition to a function for controlling the operation of various electrical components. Also it has an interface function allowing it to receive signals from the combination meter, and send signals to ECM using CAN communication.

CAN COMMUNICATION CONTROL
CAN communication allows a high rate of information transmission through the two communication lines (CAN
L line, CAN H line) connecting the various control units in the system. Each control unit transmits/receives data but selectively reads required data only. For details of signals that are transmitted/received by BCM via
CAN communication, refer to CAN System Specification Chart.

BCM STATUS CONTROL
BCM changes its status depending on the operation status in order to save power consumption.
1. CAN communication status
- With ignition switch ON, CAN communicates with other control units normally.
- Control by BCM is being operated properly.
- When ignition switch is OFF, switching to sleep mode is possible.
- Even when ignition switch is OFF, if CAN communication with IPDM E/R and combination meter is active, CAN communication status is active.
2. Sleep transient status
- This status shuts down CAN communication when ignition switch is turned OFF.
- It transmits sleep request signal to IPDM E/R and combination meter.
- Two seconds after CAN communication of all control units stops, sleep transient status is switches to
CAN communication inactive status.
3. CAN communication inactive status
- With ignition switch OFF, CAN communication is not active.
- With ignition switch OFF, control performed only by BCM is active.
- Three seconds after CAN communication of all control units stops, CAN communication inactive status is switches to sleep status.
4. Sleep status
- BCM is activated with low power mode.
- CAN communication is not active.
- When CAN communication operation is detected, it switches to CAN communication status.
- When a state of the following switches changes, it switches to CAN communication status.
- Key switch (ACC, ON)
- Key slot
- Intelligent Key (lock/unlock signal)
- Hazard switch
- Door lock/unlock switch
- Front door switch (driver side, passenger side)
- Rear door switch (LH, RH)
- Trunk lid opener switch
- Combination switch (passing, lighting switch 1ST position, front fog lamp)
- Key cylinder switch
- When control performed only by BCM is required by switch, it shifts to CAN communication inactive mode.
- Status of combination switch reading function is changed.

SYSTEMS CONTROLLED BY BCM DIRECTLY











SYSTEMS CONTROLLED BY BCM AND IPDM E/R






SYSTEMS CONTROLLED BY BCM AND COMBINATION METER






SYSTEMS CONTROLLED BY BCM AND INTELLIGENT KEY UNIT






SYSTEMS CONTROLLED BY BCM, COMBINATION METER AND IPDM E/R






SYSTEMS CONTROLLED BY BCM, LOW TIRE PRESSURE WARNING CONTROL UNIT AND

COMBINATION METER






MAJOR COMPONENTS AND CONTROL SYSTEM