Opel Frontera UBS. Service manual — part 1793
SUPPLEMENTAL RESTRAINT SYSTEM
9J–2
General Description
CAUTION: When fasteners are removed, always
reinstall them at the same location from which they
were removed. If a fastener needs to be replaced, use
the correct part number fastener for that application.
If the correct part number fastener is not available, a
fastener of equal size and strength (or stronger) may
be used. Fasteners that are not reused, and those
requiring thread locking compound will be called
out. The correct torque value must be used when
installing fasteners that require it. If the above
conditions are not followed, parts or system damage
could result.
Restraint Devices
827RW006
Legend
(1) Deployed Air Bag
(2) Knee Bolster
(3) Seat Belt
The Supplemental Restraint System (SRS) helps
supplement the protection offered by the driver and front
passenger seat belts by deploying an air bag from the
center of the steering wheel and from the top of the right
side of the instrument panel.
The air bag deploys when the vehicle is involved in a
frontal crash of sufficient force up to 30 degrees off the
centerline of the vehicle. To further absorb the crash
energy there is a knee bolster located beneath the
instrument panel for both the driver and passenger, and
the steering column is collapsible.
827RW005
SUPPLEMENTAL RESTRAINT SYSTEM
9J–3
System Description
The SRS consists of the Sensing and Diagnostic Module
(SDM), the driver air bag assembly, the SRS coil
assembly, the passenger air bag assembly and the “AIR
BAG” warning lamp in the instrument cluster. The SDM,
SRS coil assembly (driver side only), driver air bag
assembly, passenger air bag assembly and connector
wire make up the deployment loops. The function of the
deployment loops is to supply current through air bag
assembly, which will cause deployment of the air bags in
the event of a frontal crash of sufficient force, up to 30
degrees off the centerline of the vehicle. The air bag
assemblies are only supplied enough current to deploy
when the SDM detects vehicle velocity changes severe
enough to warrant deployment.
The SDM contains a sensing device which converts
vehicle velocity change to an electrical signal. The
electrical signal generated is processed by the SDM and
then compared to a value stored in memory. When the
generated signal exceeds the stored value, the SDM will
cause current to flow through the air bag assembly
deploying the air bags.
D09RW014
SUPPLEMENTAL RESTRAINT SYSTEM
9J–4
SRS Component And Wiring Location View
810RW298
Legend
(1) Battery
(2) Relay & Fuse Box
(3) Passenger Air Bag Assembly
(4) SDM
(5) Meter Assembly
(6) SRS Coil Assembly
(7) Driver Air Bag Assembly
(8) Starter Switch
(9) Fuse Box, C–21
(10) SRS Body Earth
(11) Body Harness Connector
(12) Instrument Harness Connector
(13) Engine Haness Connector
(14) Pretensioner, LH (If so equipped)
(15) Pretensioner, RH (If so equipped)
Component Description
SDM (Sensing and Diagnostic Module)
WARNING: DURING SERVICE PROCEDURES, BE
VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR
JAR THE SDM. NEVER POWER UP THE SRS WHEN
THE SDM IS NOT RIGIDLY ATTACHED TO THE
VEHICLE. ALL SDM 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 SDM COULD BE
ACTIVATED WHEN POWERED WHILE NOT RIGIDLY
ATTACHED TO THE VEHICLE WHICH COULD CAUSE
DEPLOYMENT AND RESULT IN PERSONAL INJURY.
The Sensing and Diagnostic Module (SDM) is designed
to perform the following functions in the SRS:
SUPPLEMENTAL RESTRAINT SYSTEM
9J–5
1. Energy Reserve — The SDM maintains 24–Volt Loop
Reserve (24VLR) energy supply to provide
deployment energy when ignition voltage is lost in a
frontal crash.
2. Frontal Crash Detection — The SDM monitors
vehicle velocity changes to detect frontal crashes
which are severe enough to warrant deployment.
3. Air Bag Deployment — When a frontal crash of
sufficient force is detected, the SDM will cause
enough current to flow through the air bag assembly
to deploy the air bag.
4. Malfunction Detection — The SDM performs
diagnostic monitoring of SRS electrical components
and sets a diagnostic trouble code when a
malfunction is detected.
5. Frontal Crash Recording — The SDM records
information regarding SRS status during frontal
crash.
6. Malfunction Diagnosis — The SDM displays SRS
diagnostic trouble codes and system status
information through the use of a scan tool.
7. Driver Notification — The SDM warns the vehicle
driver of SRS malfunctions by controlling the “Air
Bag” warning lamp.
The SDM is connected to the SRS wiring harness by a
24–pin connector. This harness connector uses a
shorting clip across certain terminals in the contact area.
This shorting clip connects the “AIR BAG” warning lamp
to ground when the SDM harness connector is
disconnected or CPA (Connector Position Assurance) is
not inserted even if completely connected. This will
cause the “AIR BAG” warning lamp to come “ON” steady
whenever the ignition switch is at the ON or START
positions with the SDM disconnected.
827RW044
Legend
(1) SDM
(2) SRS Harness
(3) Connector Position Assurance
“Air Bag” Warning Lamp
Ignition voltage is applied to the “AIR BAG” warning lamp
when the ignition switch is at the ON or START positions.
The SDM controls the lamp by providing ground with a
lamp driver. The “AIR BAG” warning lamp is used in the
SRS to do the following:
1. Verify lamp and SDM operation by turn on 3.5
seconds and then turns “OFF” when the ignition
switch is first turned “ON”.
2. Warn 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 “AIR BAG ” warning lamp is the key to driver
notification of SRS malfunctions. For proper lamp
operation, refer to the “SRS Diagnostic System Check” in
this section.
821RW037
SRS Coil Assembly
The SRS coil assembly consists of two current carrying
coils. This is attached to the steering column and allow
rotation of the steering wheel while maintaining
continuous contact of the driver deployment loop to the
driver air bag assembly.
There is a shorting clip on the yellow 2–pin connector near
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 air bag
assembly when the yellow 2–pin 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.
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