BCM SJB Introduction 1.1 History 1.2 Inputoutput Interface 1.3 IPS Function 2. BCM SJB Control 2.1 Main Functions 2.2 Wiper Control 2.3 Lamp Control 2.4 Central Door LockUnlock Control 2.5 Miscellaneous Controls 3. Service Procedure Function 2 BCM SJB Control 2 1 Main Functions 2 2 Wiper Contro.
Trang 1Module 2 Body Electrical Control System
1 BCM & SJB Introduction
1.1 History
1.2 Input/output Interface
1.3 IPS Function
2 BCM & SJB Control
2.1 Main Functions
2.2 Wiper Control
2.3 Lamp Control
2.4 Central Door Lock/Unlock Control
2.5 Miscellaneous Controls
3 Service Procedure
Learning
Objectives
Describe the history and features of the body control module.
Describe the body control module's control functions and processes.
Perform body control module service procedures.
Trang 31 System Introduction
Body electrical systems were developed for the speedy control of modules required for the application of various convenience functions in vehicles The Body Electrical System is the system that provides integrated control for various convenient features of a vehicle It supports controls for the wiper system, lamp system, central door lock/unlock system, and theft alarm system The history of body electrical systems is summarized below
1) ETACS
ETACS is the acronym for Electronic Time Alarm Control System Its controls the timer (heating wire timer and power window timer), alarm (seat belt alarm, door open alarm, etc.), lamps and door lock Vehicles with an ETACS receive all switch data related to body electrical system control through the ETACS Relay, actuator and motor control was also performed by the ETACS Communication with diagnostic equipment is not possible as no communication IC
is installed ETACS is not used in modern vehicles
2) BCM
BCM is the acronym for Body Control Module It is the successor to the ETACS Its difference from the ETACS is that communication with diagnostic equipment is possible Although individual vehicles models vary, the control of a BCM is similar to that of an ETACS Diagnostic equipment communication allows the viewing of current data on input/output elements, and actuation tests can be carried out
3) BCM + SJB
As BCMs started to use CAN communication and more functions became required of them, the SJB (Smart Junction Box) was applied to BCMs Like BCMs, SJBs receive switch data and drive actuators A SJB is connected to a BCM via CAN communication to receive BCM commands and drive actuators The BCM + SJB combination is the most common body electrical system used today
4) IPM
IPM is the acronym for Intelligent Integrated Platform Module, which combines all the functions
of a BCM and SJB Switch signals are received from modules related to control functions for actuator output IPMs are mainly found in luxury vehicles
1.1 System History
Trang 4The most important function of a body electrical system is receiving switch signals and producing an appropriate output The input and output of signals is closely related to Basic Electrics and Electronics Take a look at the following diagram
1.2 Input/output Interface
Ground
B+ Power
Power
Relay
Switch 1
C P U
5V TR
1) Input
Switch input shows that voltage of 5V is sent to the switch from the body electrical system If the switch operates, the pull-up voltage of 5V falls to 0V The BCM detects this voltage drop and recognizes the switch operation This is called the pull-up method As explained in Basic Electrics and Electronics, there is also the pull-down method, which immediately inputs 12V upon switch operation, in addition to the pull-up method
2) Output
Upon switch input detection, the body electrical system must drive the relays to switch on the lamps The body electrical system sends output currents to the transistor to drive the transistor that controls the relays When the transistor switches on, the relays become magnetized and lamps operate If output is executed by a module other than the one that detected the switch signal, the "switch on" signal is sent to the module responsible for output through the communication line
The system's input/output components increased significantly as a vehicle's control features increased The trend in recent models is the change from the ground output control using transistor to power output control using the IPS to actively respond to potential problems created at the output terminal
In short, a body electrical system controls output when input conditions are met The pull-up method and pull-down method are mainly used for input monitoring Output control takes place through transistor-based relay ground control or IPS-based control
Trang 5IPS stands for Intelligent Power Switching device, which is an output device that can replace a relay and fuse IPS uses a semiconductor device and is being widely applied to body electrical system output control In addition to output control, IPS can detect and manage a circuit disconnection, short circuit or overload Other features include a self-check function, compact size and multi-channel control
1.3 IPS
Relay + fuse = IPS
Currently, IPS is being widely used for smart
junction box output control An IPM can also
use an IPS for output control
IPS is mainly used for the control of vehicle lamp (head lamps, indicators, tail lamps and fog lamps) output The key functions of IPS are as follows
A device that integrates four IPS units Performs the function of four IPS units simultaneously 4As four IPS units are combined into a single package, there is ample space and simplified software is used.
<Refer to: ARISU – LT>
1) Wiring protection
PCL (Programmable Circuit Limit) function
Application Range All the lamp loads controlled by IPS (head lamp, fog lamp, tail lamp)
Current detection If over current flows, cuts off the power within 300 ms and record the
event for diagnosis
Deactivation
Conditions
When the shut off switch returns to On (when no over current is detected), after the lamp switch where over current is detected has been turned Off
When the switch returns to On after IGN Off (when no over current is detected)
Fuse is removed on IPS applied circuit IPS directly detects the current flowing through the circuit and, if over current is detected, the IPS cuts off power to the corresponding circuit
The following diagram shows how IPS detects and cuts off overcurrents
Trang 6Fuse and relay control IPS Control
Interior junction box
BCM
ⓐ Short circuit
ⓑ Overcurrent flow
ⓒ Fuse Disconnection
B+
SJB
MCU
ⓒ Transmit current information
ⓓ Prevent control if overcurrent is detected and record Lamp status
B+
ⓐ Short circuit
ⓑ Overcurrent flow
In the case where a fuse was used, it got disconnected from an overcurrent when a short circuit occurred in the lamp circuit
The following is the application of an IPS Circuit currents are constantly monitored by the IPS When an overcurrent is detected, data is sent to the controller of the SJB The SJB immediately stops IPS operation to prevent circuit damage
OCL (Open Circuit Limit) function
Different than the PCL, the OCL detects disconnection and notifies the driver if the circuit is disconnected OCL is applied to indicators and hazard lamps to speed up their blinking in the event of a lamp disconnection
Application Range
The OCL is applied only to the turn signal lamp and hazard lamp, and detects the circuit disconnection (bulb out of socket) and controls the remaining bulbs to make them blink faster
Current detection Detects disconnection when the current flowing in the turn signal lamp
circuit is below 1 A and records the occurrence for diagnosis
Deactivation
Conditions
When the shut off switch returns to On, after the lamp switch where disconnection was detected has been turned Off
When the switch returns to On after IGN Off and normal current is detected
If the lamp circuit gets disconnected while IPS is monitoring circuit currents, current detection will indicate 0 As well, circuit disconnection data is sent to the SJB controller The SJB then blinks all the lamps except the disconnected one quickly to notify the user of the lamp failure
Trang 72) Overvoltage protection (PWM control)
The voltage applied to the lamp varies depending on the generated voltage If the generated voltage is low, then there's not enough illumination, and if the generated voltage is high, then the life span of the lamp is shortened The SJB controls the PWM to keep input voltage at 13.2V to increase lamp life span Protection against surge voltage is applied to below 3 devices
Head lamp low LH/RH (The surge voltage protection feature is not applicable for HID option)
Head lamp high LH/RH
Front fog lamps (LH/RH) and tail lamps (LH/RH)
PWM control is not required for HID lamps as they have a built-in voltage booster called Ballast
☞ Pulse Width Modulation (PWM) can maintain constant voltage by modulating the pulse width.
SJB
Controller IPS
ADC Circuit
B＋(surge voltage inlet)
.
Maintain 13.2V rated voltage
☞ If less than 13.2V is inputted, PWM is not activated
0V
12V
30%
70%
0V 12V
50%
50%
If the pulse width is narrow If the pulse width is wide
If 12 V is controlled at 70% On and 30% Off as
shown in the diagram, the average voltage is
maintained at approximately 8 V.
If 12 V is controlled at 50% On and 50% Off as shown in the diagram, the average voltage is maintained at approximately 6 V.
Trang 82 Control
While body electrical systems differ by vehicle, they perform the following functions in general
Warning
Seat belt warning, Seat belt reminder , Alarm buzzer RPAS indicator/buzzer control, RKE teaching
Sun roof open warning, Parking brake warning, Key reminder B/Alarm Anti-theft control
Timer Rear defogger, Front deicer, Power window control
Door
Central door lock/unlock by switch/key/RKE/SMK, Key reminder Auto door lock (Shift from P, Vehicle speed 15kph) control Auto door unlock (Crash, Shift to P, Key out) control, Tailgate unlock Safety Ignition key interlock, ATM shift lock control
EXT lamp
Tail lamp control by switch / auto cut, Auto light Headlamp control by switch / auto light, escort control Puddle & Pocket lamp control, Hazard lamp, Fog lamp control
INT lamp Room lamp delay control, Map lamp delay control
Wiper Front wiper: intermittent, washer, mist
Rear wiper: intermittent, washer, on/off etc AV unlock output, Auto mirror folding & unfolding
2.1 Main Functions of the Body Electrical System
The body electrical system controls the lamps, wipers, power door lock, timer and alarm In this lesson, some of the main control functions of the body electrical system will be explained
Trang 92.2 Wiper Control
R LO H
I IG N M W INT INT. T E
Wiper control takes place as follows The wipers are independently controlled by the BCM without the SJB When the LOW or HIGH function is used, power is supplied to the wiper motor without BCM intervention (In some vehicles, the wiper LOW and HIGH functions are also controlled by the BCM.)
WIperINT and MIST functions are controlled by the BCM When the switch is operated, the BCM receives switch signals and operates the transistor that controls the wiper relay When the wiper relay becomes magnetized, IGN power is supplied to the motor after passing through the internal contact of the multi-function switch
The windscreen washer function is also controlled by the BCM Positioning the switch to
"washer" immediately activates the washer motor and the wipers are controlled at LOW speed
by the BCM
Regardless of the wipers' current position, when the wiper switch is set to "off," the wipers return to their original position This function is in place to prevent the wipers from stopping in the middle of movement when the switch is set to "off." When the wipers are operating, the parking switch inside the wiper motor is always mechanically connected to IG power This keeps supplying power to the wiper motor even when the switch is set to "off." When the wipers return to their original position, the parking switch connects to the ground mechanically
C
U
IG
Wiper Relay
Wiper Motor
Washer Motor
Parking
Multifunction Switch
BCM
Vertical: switch position
Horizontal: Output terminal for switch position
The table indicates internal burn-in for the switch
position.
Trang 102.3 Lamp Control
LOW and HIGH switch signals for the tail lamps and head lamps are detected by the BCM The BCM give IPS output commands to the SJB through B-CAN communication Then, the SJB produces tail/head lamp output through the IPS The SJB sends an output completion signal to the BCM to determine system soundness At the same time, data is sent to the cluster through CAN communication to light up the indicators
If an auto light function is present, auto light switch signals are also detected by the BCM If the light level sensor reading sent to the BCM indicates that lamps need switching on, the BCM sends an IPS output command to the SJB to switch on the lamps
1) Tail Lamp & Head Lamp Control
2) Indicators & Hazard Lamp Control
SJB
Lamp Control request
Lamp output completion signal
Current Value Feedback &
failure information
Control Signal
IPS
IPS
CPU
BCM
Tail Lamp
Head lamp
Tail lamp switch
Head lamp
LOW switch
Head lamp
HIGH switch
Autolight switch
Cluster Ambient
Light Sensor
SJB
Indicator and hazard lamp control through switch operation is processed by the SJB alone Indicator and hazard lamp switch signals are input directly in the SJB The SJB activates lamps
by operating the indicator sound relay and IPS At the same time, data is sent to the cluster through the CAN line to light up the indicators The indicators can be switched on when the ignition is both on or off
Hazard lamp blinking by the RKE is collectively triggered by the BCM and SJB When the BCM receives RKE remote control data, a hazard lamp activation command is given to the SJB through CAN communication
Front left turn signal lamp
SJB
IPS Control Hazard Lamp Switch
Left turn signal lamp switch
Right turn signal lamp switch
Rear left turn signal lamp Front right turn signal lamp Rear left turn signal lamp
Cluster Turn signal lamp
sound relay CPU
BCM
Lamp Control request
Trang 11The tail lamp automatically turns off when removing the key and opening the door.
Tail lamp "on" signals are detected by the SJB Turning off the ignition and opening the driver side door sends a "driver door open" signal to the SJB The SJB sends door switch data and tail lamp switch data to the BCM The BCM sends a "tail lamp off" signal to the SJB and the SJB turns off the tail lamps
3) Tail Lamp Auto Off Control
4) Head Lamp Escort Control
The head lamp escort function is only enabled when the escort function is switched on in the USM With the head lamp escort function, turning off the ignition while the head lamps are on keeps them on for about 20 minutes (can vary by vehicle model) before switching off
Head lamp "on" signals are detected by the BCM Switching off the ignition makes the BCM give the "head lamps off" command to the SJB after 20 minutes
Closing all doors after switching off the ignition sends a door switch signal to the SJB If the remote control lock or passive lock switch is pressed, the BCM detects the signal and activates the anti-theft mode When this happens, a "head lamps off" command is given to the SJB after
30 seconds
Pressing the remote control lock button twice while in anti-theft mode sends a signal to the
Tail Lamp OFF
Driver Side Door Switch SJB
IPS Control CPU
BCM
Switch Signal Tail Lamp OFF Tail Lamp Switch
Head lamp OFF
Door switches (four total)
Hood Switch Trunk Switch
SJB
IPS Control CPU
BCM
Switch Signal Head Lamp OFF
SMK Passive lock
H/Lamp Low
Auto light