Daewoo Korando. Manual - part 325

SUPPLEMENTAL RESTRAINT SYSTEM(SRS) 8B-3

FUNCTION DESCRIPTION

Air Bag Control Unit (AC4)

Air bag control unit (AC4) is installed on the center portion of
the front floor tunnel.

It is a central control unit that control all functions and determines
whether deploy the air bag or not with the collision signal from
the built-in accelerometer sensor and has function of diagnosing
system defects.

Internal air bag control unit is consisted as follows;

Microprocessor

ASICs (Upper side ASIC & lower side ASIC)

Accelerometer sensor

Arming sensor

System energy backup condenser

Squib energy backup condenser

8B-4 SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

Input & Output Function

Electronic air bag control and diagnosis module is connected
by full 30-pin connectors.

Input : ground

Output : 1 squib line, warning lamp

Input/output : communication, diagnosis

16 Shorting Bar
17 Shorting Bar
18 Shorting Bar
19 Shorting Bar
20 Diagnosis
21 Shorting Bar
22 Shorting Bar
23 No Pin
24 No Pin
25 Shorting Bar
26 Shorting Bar
27 N/A
28 Shorting Bar
29 Shorting Bar
30 N/A

1 Lamp
2 Ground
3 N/A
4 N/A
5 Ignition
6 N/A
7 N/A
8 CONF
9 N/A

10 N/A

11 N/A

12 N/A
13 Squib Line 1(upper)
14 Squib Line 1(lower)
15 N/A

IGN

GND

Warning lamp

RxD/TxD

Inflator line 1

Air bag lamp

Communication/
diagnosis

Air bag

control

unit

Ground connection or open

Connector Pins

SUPPLEMENTAL RESTRAINT SYSTEM(SRS) 8B-5

Air Bag Module

Air bag module is installed in the pad of steering wheel center and inflator is consisted of igniter, explosives, gas
generating material and bag. When crashed, the air bag control unit sends current to the air bag module through
squib line and this current ignites as ignition energy (6mJ) momentarily igniting explosives and bag will be inflated
by nitrogen gas protecting driver at the same and then deflates.

1 Air bag Module
2 Module Housing
3 Bag
4 Module Bracket

5 Retainer Ring
6 Inflator
7 Horn Switch
8 Backing Plate

8B-6 SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

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.

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