Hyundai Elantra: Fuses And Relays / Relay Box (Passenger Compartment) Description and Operation

Hyundai Elantra AD (2016-2020) Service Manual / Body Electrical System / Fuses And Relays / Relay Box (Passenger Compartment) Description and Operation

Description

Auto Cut System of Dark Current

Abbreviation	Expalnation
ACU	Airbag Control Unit
ADM	Assist Door Module
B_CAN	Body Controller Area Network
BCM	Body Control Module
BSD	Blind Spot Detection
C_CAN	Chassis Controller Area Network
CLU	Cluster Module
DATC	Dual Automatic Temp Control
DDM	Driver Door Module
ESC	Electronic Stability Program
EMS	Engine Management System
LKAS	Lane Keeping Assist System
M_CAN	Multi media Controller Area Network
MDPS	Motor Driven Power Steering
P_CAN	Powertrain Controller Area Network
PSM	Power Seat Module
SAS	Steering Angle Sensor
SJB	Smart Junction Block
SMK	Smart Key Unit
PAS	Parking Assist System
TCU	Transmission Control Unit
TPMS	Tire Pressure Monitoring System
VDC	Vehicle Dynamic Control
TMU	Telematics System
ABS	Anti-lock Brake System
SCC	Smart Cruise Control

Smart Junction Block (SJB)

General function : Interior Junction Block + some functions of BCM

It controls loads with CAN communication and IPS.

IPS stands for Intelligent Power Switch, which uses the semiconductor technology to replace the current role of fuse and relay. (The IPS device protects the current load control function from the overcurrent.)

The advantages of IPS are as follows:

-	Reduce relay and consequently decrease weight and volume

-	Remove the relay operation noise

-	Not necessary to replace fuse, increasing the product life

-	Diagnosis capability

SJB control entry

Switch signal input

(1)

Assist seat belt switch

Assist the door switch

Driver's seat belt switch

Rear left door switch

Rear right door switch

IGN1 switch

IGN2 switch

Brake fluid sensor

Trunk lid handle switch

HID head lamp option

Hazard lamp switch

Head lamp low beams switch

Hood switch

Left front / rear turn signal switch

Right front / rear turn signal switch

Parking brake switch

Driver the door lock/unlock control status

Assist the door lock/unlock control status

Rear left the door lock/unlock status

Rear right the door lock/unlock status

Driver the door switch

Driver the door key lock switch

Driver the door key unlock switch

Driver the door power window lock switch

Driver the door power window unlock switch

(2)

IPS&ARISU

Left Head lamp low beams

Right Head lamp low beams

Left Head lamp high beams

Right Head lamp high beams

Room lamp

Exterior left tail lamp

Exterior right tail lamp

Left front / rear turn signals

Right front / rear turn signals

DRL left lamp

DRL right lamp

Body resistance cut control

Front left turn signal output

Front right turn signal output

(3)	Relay Control Rear glass heater relay Trunk lid relay Front glass heater relay Head lamp high beams relay Memory fuse switch relay Door lock/unlock relay Power window wake-up relay 2 Turn door lock relay

SJB protection

(1)

PCL (Programmable Current Limit) functions

A.	Replace the current junction box fuse function to protect the wire.

B.	How to operate : If the lamp current exceeds the standard level, cut off the lamp current to protect lamp.

C.	Lamp cut off time : 300ms or less.

D.	Applied load : Applied to all lamp loads controlled by SJB.

E.	Output the error code according to the error detection conditions.

(2)

OCL (Open Current Limit)

A.	Detect the lamp open state and inform the user of it.

B.	How to operate: Detect the current of the lamp and if it is below the standard level, change the lamp operation.

C.	Applied load: Applied to the turn signal lamp 4 channel

D.	Output the error code according to the error detection conditions.

SJB fail safe function

(1)	When SJB has a failed MCU (not operating due to a physical or electrical shock from the outside), the head lamp low and exterior and interior tail lamp are turned on to secure the driver if IGN2 is on and the head lamp low switch is on.

(2)

When the data transmission/reception fails due to a failed CAN communication line connected with SJB module (disconnection of both high and low line, high/low BAT short, high/low GND short), the head lamp low and interior/exterior tail lamps are turned on if IGN2 is on and the head lamp low switch is on.

Auto Cut System of Dark Current

(1)	Description : It cuts automatically power to be provided with load for reducing useless dark current according to vehicle state.

(2)

SJB had 3 modes, "Normal Mode", "Sleep Mode", "Power Off Mode". Auto cut of dark current practice in "Sleep Mode".

A.	"Sleep" condition : IG OFF, constant input switch, CAN network doesn't activate.

B.	"Sleep" resolutive condition : Any switch inputs, CAN network activates, KEY ON, IGN ON

C.	"Power OFF" condition : The setting time of timer which is used by cutting a load power expires.

D.	"Normal Mode" : SJB function normally activates.

E.	"Sleep Mode" : It is low power mode and activates for reducing electricity consumption of SJB or IPM. Auto cut of dark current function activates.

F.	"Power OFF Mode" : Power of MCU and circumferential circuit is cut for minimizing electricity consumption. Operation stops.

(3)

The explanation - The auto cut of dark current

Before delivering to customer

Fuse switch OFF

•	All door close & RKE door lock or Constant switch state (Auto cut of dark current scenario starts.)

-	After "Sleep" state is for 5 min.

-	SJB power down(SJB dark current : 200 ?A) and cutting power of Lamp /Multimedia Load/Wake up/Immobilzer

After delivering to customer

Fuse switch ON

•	All door close & Constant switch state : C_BAState=OFF (Auto cut of dark current scenario starts.)

-	After "Sleep" state is for 20 min.

•	In case RKE door lock : C_BAState=ON & Trunk SW=CLOSE (Auto cut of dark current scenario starts.)

-	After "Sleep" state 35s~65s (Waiting time of other unit : 30~60s + SJB sleep counts 5s)

(4)

Problem when fuse switch setting is wrong

: If a fuse switch is set to OFF(Before delivering to customer) by a customer or technician and auto cut function of dark current activates, below problems may happen.

Symptom

Related part

•	Door lock/unlock, trunk open don't activate by RKE. (Wakeup of each module don't activate.)

BCM

•	Digital clock is reset.(Memory is reset.)

Digital clock

•	Setting value of audio(Volume, Frequency setting) is reset. (Memory is reset.)

Audio

* If fuse switch OFF (before delivering to customer) is set, power of BCM, Digital clock and audio is shut off.

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