ISUZU KB P190 2007 Workshop Repair Manual

9A-6 SUPPLEMENTAL RESTRAINT SYSTEM
Circuit Diagram
4JJ1-TC, 4JK1-TC (Except South Africa)


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SUPPLEMENTAL RESTRAINT SYSTEM 9A-7
4JJ1-TC (South Africa)


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9A-8 SUPPLEMENTAL RESTRAINT SYSTEM
4JH1-TC, 4JA1-L

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SUPPLEMENTAL RESTRAINT SYSTEM 9A-9
C24SE


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9A-10 SUPPLEMENTAL RESTRAINT SYSTEM
SRS Component And Wiring Location View
Parts Location (RHD) (1)




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SUPPLEMENTAL RESTRAINT SYSTEM 9A-11
Parts Location (RHD) (2)

RTW 78AXF046501



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9A-12 SUPPLEMENTAL RESTRAINT SYSTEM
Parts Location (LHD) (1)



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SUPPLEMENTAL RESTRAINT SYSTEM 9A-13
Parts Location (LHD) (2)


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9A-14 SUPPLEMENTAL RESTRAINT SYSTEM
Component Description
SRS Control Unit
WARNING: DURING SERVICE PROCEDURES, BE
VERY CAREFUL WHEN HANDLING A SRS
CONTROL UNIT. NEVER STRIKE OR JAR THE SRS
CONTORL UNIT. NEVER POWER UP THE SRS
WHEN THE SRS CONTROL UNIT IS NOT RIGIDLY
ATTACHED TO THE VEHICLE. ALL SRS CONTROL
UNIT AND MOUNTING BRACKET FASTENERS
MUST BE CAREFULLY TORQUED AND THE
ARROW MUST BE POINTED TOWARD THE FRONT
OF THE VEHICLE TO ENSURE PROPER
OPERATION OF THE SRS. THE SRS CONTROL
UNIT COULD BE ACTIVATED WHEN POWERED
WHILE NOT RIGIDLY ATTACHED TO THE
VEHICLE WHICH COULD CAUSE DEPLOYMENT
AND RESULT IN PERSONAL INJURY.
The SRS control unit is designed to perform the
following functions in the SRS:
1. Energy Reserve — The SRS control unit maintains 30–Volt Loop Reserve (30VLR) energy supply to
provide deployment energy when ignition voltage is
lost in a frontal crash.
2. Frontal Crash Detection — The SRS control unit monitors vehicle velocity changes to detect frontal
crashes which are severe enough to warrant
deployment.
3. Air Bag Deployment — W hen a frontal crash o
f
sufficient force is detected, the SRS control unit
will cause enough current to flow through the ai
r
bag assembly to deploy the air bag.
4. Malfunction Detection — The SRS control unit performs diagnostic monitoring of SRS electrical
components and sets a diagnostic trouble code
when a malfunction is detected.
5. Frontal Crash Recording — The SRS control unit records information regarding SRS status during
frontal crash.
6. Malfunction Diagnosis — The SRS control unit displays SRS diagnostic trouble codes and system
status information through the use of a scan tool.
7. Driver Notification — The SRS control unit warns the vehicle driver of SRS malfunctions b
y
controlling the “SRS” warning lamp.


The SRS control unit is connected to the SRS wiring
harness by a 52–pin connector. This harness
connector uses a shorting clip across certain terminals
in the contact area. This shorting clip connects the
“SRS” warning lamp to ground when the SRS control
unit harness connector is disconnected or CP
A
(Connector Position Assurance) is not inserted even i
f
completely connected. This will cause the “SRS”
warning lamp to come “ON” steady whenever the
ignition switch is at the ON or START positions with
the SRS control unit disconnected.


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Legend
(1) SRS Control Unit
(2) SRS Harness


“SRS” Warning Lamp
Ignition voltage is applied to the “SRS” warning lamp
when the ignition switch is at the ON or START
positions. The SRS control unit controls the lamp b
y
providing ground with a lamp driver. The “SRS”
warning lamp is used in the SRS to do the following:
1. Verify lamp and SRS control unit operation b
y
flashing SEVEN (7) times when the ignition switch
is first turned “ON”.
2. W arn the vehicle driver of SRS electrical system malfunctions which could potentially affect the
operation of the SRS. These malfunctions could
result in nondeployment in case of a frontal crash
or deployment for conditions less severe than
intended.
The “SRS “ warning lamp is the key to drive
r
notification of SRS malfunctions. For proper lamp
operation, refer to the “SRS Diagnostic System Check”
in this section.

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SUPPLEMENTAL RESTRAINT SYSTEM 9A-15



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SRS Coil Assembly
The SRS coil assembly consists of two current
carrying coils. This is attached to the steering column
and allows rotation of the steering wheel while
maintaining continuous contact of the drive
r
deployment loop to the driver air bag assembly.
There is a shorting clip on the yellow connector nea
r
the base of steering column which connects the SRS
coil to the SRS wiring harness.
The shorting clip shorts to the SRS coil and driver ai
r
bag assembly when the yellow connector is
disconnected. The circuit to the driver air bag
assembly is shorted in this way to help prevent
unwanted deployment of the air bag when servicing
the steering column or other SRS components.

060R300047
Air Bag Assemblies
The air bag assembly consists of an inflatable air bag
assembly and an inflator. W hen the vehicle is in a
frontal crash of sufficient force the SRS control unit
causes current flow through the deployment loops.
Current passing through the inflator ignites the
material in the air bag assembly. The gas produced
from this reaction rapidly inflates the air bag assembly.
There is a shorting clip on the driver air bag assembl
y
connector which connects the SRS coil assembly. The
shorting clip shorts across the driver air bag assembl
y
circuits when the driver air bag assembly connector is
disconnected.
The circuit to the driver air bag assembly is shorted in
this way to help prevent unwanted deployment of the
air bag when servicing the driver air bag assembly, the
steering column or other SRS components.




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There is a shorting clip on the passenger air bag
assembly connector which connects to the SRS
harness. The shorting clip shorts across the
passenger air bag assembly circuit when the
passenger air bag assembly connector is
disconnected. The circuit to the passenger air bag
assembly is shorted in this way to help prevent
unwanted deployment of the air bag when servicing
the passenger air bag assembly, the instrument panel
or other SRS components.


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