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SUPPLEMENTAL RESTRAINT SYSTEM(SRS) 8B-7
DIAGNOSIS
DESCRIPTION
Air bag control unit continuously controls system function as follows during ignition ON or driving.
- Recognition of collision
- Internal diagnosis
- External diagnosis
If recognize or detect defects, warning lamp will turn on. If there is danger of improper deployment, the system will
enter overall shutdown status and the air bag will not inflate.
Air bag control unit will store detected internal and external defects in the EEPROM.
System Control
Battery Voltage Check
Battery voltage will be monitored continuously. If voltage is out of normal operating range, all system diagnosis will
stop and warning lamp turn on.
Battery Voltage (V)
< 8.7
9 - 16
> 16.3
Function
System diagnosis stops and warning lamp turns on
Normal operation range
System diagnosis stops and warning lamp turns on
Squib Diagnosis
It checks not only high (4.50.5) or low (1.40.5) resistance but also short resistance (1- 10k) status between the
battery and ground to indicate defects in squib line by blinking warning lamp. Air bag control unit (AC4) can measure
squib resistance.
Warning Lamp Turning On
Air bag control unit detects system defects during ignition ON or driving and displays following 2 warning lamps.
- Warning lamp ON: internal defects of the air bag control unit
- Warning lamp blinking: higher resistance than standard in the squib line or short at the battery or ground,
Safety Function Check
It checks defects during operation of the arming sensor If the sensor is shorted for more than 2 seconds, the module
will enter overall shutdown mode.
Temperature Sensor
Function of the temperature sensor will be monitored continuously. If there is fault due to defective sensor or short,
the lamp will turn on and program will take calibration temperature (25) of collision conditions.
Power Supply
Airbag control unit operates in 9-16v and the characteristic of the system has backup condenser to supply the power
for max.150ms if there is power defect during collision.
Page 1313 of 1463

SUPPLEMENTAL RESTRAINT SYSTEM(SRS) 8B-9
Diagnosis
Air bag control unit diagnoses each function in the intervals of 250ms - 20 sec. during start-up or driving to prevent
unwanted air bag deployment. If there is defect, it turns on or blinks warning lamp to indicate defects in the air bag
system to the driver. And fatal defect is found, air bag control unit enters overall or partial shutdown status and fault
code will be stored.
Air bag control unit diagnoses following items.
- Ignition TR
- Acceleration
- Microprocessor, RAM and ROM
- Watchdog
- Shutdown Switch
Diagnosis Condition Diagnosis Items
Start-up (ignition ON)
During Driving
Lamp Blinking Mode
There are 2 kinds of blinking mode
1. When system internal fault is found, the lamp will stay on.
2. The lamp will blink according to external fault and there are 2 blinking codes.
Blinking code 1 (Squib resistance fault in the driver’s air bag squib line)
Blinking code 2 (Squib short on plus and minus in the air bag squib line)
Lamp blinking code is as follows. The last blinking will be within 0.5 sec. and 1 cycle of blinking will be repeated every
5 seconds.
Blinking Code 1
(Sec.) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Blinking Code 3
(Sec.) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
- Squib resistance
- Squib line short to battery and ground
- Energy reserve system
- Lamp output
- Battery voltage
- ASIC communication
- Arming sensor
- ASIC overheating
- RAM and W/D
- EEPROM
Page 1433 of 1463

REMOTE KEYLESS ENTRY AND ANTI-THEFT SYSTEM 9T-3
DIAGNOSIS TEST
Introduction
Using the service connector, possible defects in power section,
input·output section of internal STICS unit can be detected and
each normal status and defect mode can be checked.
Diagnosis Method
1. Use buzzer for diagnosis check status output.
2. Following function outputs should not act when diagnosis
switch is ON (STICS in the diagnosis socket box:connection
of No. 7 and ground No.1).
- Tail lamp ON warning (buzzer output stop, door lock/
unlock output stop)
- Seat belt warning (chime bell output stop)
- Key reminder warning (chime bell output stop, door lock/
unlock output stop)
- Central door lock (door lock/unlock output stop)
3. Functions in No. 2 should be restored when diagnosis switch
is OFF.
4. Checked output should be made once while the diagnosis
switch is ON.
5. When inputs are made by operating each different switches
more than 2 continuously, make output according to input
order (buzzer ON) and turn off the buzzer for 1 second and
than make other remaining outputs for input switch.
DIAGNOSIS
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