Airbag (SRS): Overview Saab 9-4X I

SIR Identification Views

The SIR Identification Views shown below illustrate the approximate location of all SIR components available for the vehicle. This will assist in determining the appropriate SIR Disabling and Enabling for a given service procedure, refer to SIR DISABLING AND ENABLING .

Scheme 1

1. (1) Right Front Impact Sensor-Located on the front of the vehicle in the engine compartment
2. (3) Passenger Instrument Panel Air Bag-Located at the top right under the instrument panel
3. (4) Right Roof Rail Air Bag - Located on the upper quarter panel behind the garnish, extending from the passenger front windshield pillar to the rear window pillar.
4. (5) Inflatable Restraint Sensing and Diagnostic Module (SDM)-Located underneath the vehicle carpet under the center console
5. (6) Right Front Side Impact Sensor-Located inside front passenger door
6. (7) Passenger Presence System-Located under the front passenger seat trim cover
7. (8) Passenger Seat Belt Anchor Pretensioner-Located on the outboard side of the passenger seat
8. (9) Passenger Seat Side Air Bag-Located on the seat back of passenger seat
9. (10) Passenger Seat Belt Retractor Pretensioner-Located under the trim near the bottom of the center pillar
10. (11) Right Rear Side Impact Sensor-Located inside rear passenger door
11. (13) Vehicle battery-Located in the engine compartment on the driver's side.
12. (15) Left Rear Side Impact Sensor-Located inside rear passenger door
13. (16) Driver Seat Belt Retractor Pretensioner-Located under the trim near the bottom of the center pillar
14. (17) Driver Seat Side Air Bag-Located on the seat back of driver seat
15. (18) Driver Seat Belt Anchor Pretensioner-Located on the outboard side of the driver seat
16. (19) Left Front Side Impact Sensor-Located inside driver door
17. (20) Left Roof Rail Air Bag-Located on the quarter panel upper, extending from the driver front windshield pillar to the driver rear windshield pillar
18. (21) Driver Steering Wheel Air Bag-Located on the steering wheel
19. (22) Left Front Impact Sensor-Located on the front of the vehicle in the engine compartment

SIR System Overview

The airbag system (SIR) complements the protection that the seat belts give. The SIR system incorporates a module for sensing and diagnosis (SDM), airbags, belt pretensioner (mounting and belt reel) and collision sensors. The SDM determines the severity of a collision using collision sensors strategically placed within the car. When the SDM senses a collision it analyzes the information from the sensors to assess the need to activate the airbags and belt pretensioners. The SDM deploys the airbags and belt pretensioners if it senses that the collision forces are sufficiently severe. If the collision force is insufficient for activation of the airbags, the SDM can deploy the seat belt pretensioners. The SDM incorporates a sensor unit that produces an electric signals that are proportional to vehicle speed rates of change. The SDM compares these signals with values that are stored in memory. If the signals exceed the stored values, the SDM determines the force of the collision and either transmits a current through the front activation circuits to deploy both the front airbags and belt pretensioners or only deploys the pretensioners. The SDM continually monitors the deployment circuits for faults and illuminates the SIR system AIRBAG indicator if a fault is detected. The SDM continually carries out diagnosis monitoring on the SIS electrical components. When the SDM senses a circuit fault it sets a DTC and informs the driver by illuminating the SIR system AIRBAG indicator. The steering column and knee bolsters are designed to absorb energy and are collapsed in frontal impacts to limit leg movements and minimize the risk of injuries to the driver and passengers.

Circuit/System Description

During a frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the steering wheel air bag. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. There are 2 shorting bars used within the steering wheel air bag coil connector which will short together both steering wheel air bag stage 1 high control circuit and steering wheel air bag stage 1 low control circuit and both steering wheel air bag stage 2 high control circuit and steering wheel air bag stage 2 low control circuit when the connector is disconnected. This will help to prevent unwanted deployment of the steering wheel air bag during servicing.

Description and Operation

SIR SYSTEM DESCRIPTION AND OPERATION

During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy an air bag. There are 2 shorting bars used within the connector that will short together the control circuits, when the connector is disconnected. This will help to prevent unwanted deployment of the air bag or retractor pretensioner during servicing.

SIR SYSTEM DESCRIPTION AND OPERATION

During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy an air bag or pretensioner. There are 2 shorting bars which will short together control circuits, when the connector is disconnected. This will help to prevent unwanted deployment of the air bag or pretensioner during servicing.

SIR SYSTEM DESCRIPTION AND OPERATION

During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy an air bag or pretensioner. There are 2 shorting bars which will short together control circuits, when the connector is disconnected. This will help to prevent unwanted deployment of the air bag or pretensioner during servicing.

SIR SYSTEM DESCRIPTION AND OPERATION

During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy an air bag or pretensioner. There are 2 shorting bars which will short together control circuits, when the connector is disconnected. This will help to prevent unwanted deployment of the air bag or pretensioner during servicing.

SIR SYSTEM DESCRIPTION AND OPERATION

During side or frontal impact with sufficient force the Inflatable restraint sensing and diagnostic module (SDM) will permit voltage through the activation loop to activate the airbag or pretensioner. There are two short pins that make the control circuit when the connector is taken apart. This prevents accidental activation of the airbag or pretensioner during service.

SIR SYSTEM DESCRIPTION AND OPERATION

The inflatable restraint sensing and diagnostic module (SDM) senses vehicle impacts and provides deployment signals to the air bags and anchor and/or retractor pretensioners when warranted. The SDM sets DTC B0052 after each deployment command. DTC B0052 will latch and not clear after 3 commanded deployments by the SDM. And therefore the SDM has to be replaced using end of life disposal procedure.

The passenger presence module monitors the sensor status continually. Whenever the sensor mat has an internal malfunction, the passenger presence module will set DTC B0074.

SIR SYSTEM DESCRIPTION AND OPERATION

When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) and the passenger presence module perform tests to diagnose critical malfunctions. Upon a successful power-up mode the SDM will illuminate both PASSENGER AIRBAG ON/OFF indicators. If the SDM detects a fault in the passenger presence module, it may disable the passenger instrument panel air bag deployment loop, set DTC B0081 and illuminate the AIRBAG indicator.

SIR SYSTEM DESCRIPTION AND OPERATION

When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) and the passenger presence module perform tests to diagnose critical malfunctions. Upon a successful power-up mode the SDM will illuminate both PASSENGER AIRBAG ON/OFF indicators. If the SDM detects a fault in the passenger presence module, it may disable the passenger instrument panel air bag deployment loop, set DTC B0081 00 or DTC B0081 3A and illuminate the AIRBAG indicator.

SIR SYSTEM DESCRIPTION AND OPERATION

The seat belt reminder sensor is in the passenger seat cushion and provides an input to the inflatable restraint sensing and diagnostic module (SDM). The SDM supplies a low reference circuit and a seat belt reminder sensor signal circuit to determine whether or not the seat is occupied.

SIR SYSTEM DESCRIPTION AND OPERATION

The impact sensors are equipped on vehicles to supplement the Supplemental Inflatable Restraint (SIR) System performance. The impact sensors are electronic and are not part of the deployment loops, but instead provide inputs to the sensing and diagnostic module (SDM). The impact sensors can assist in determining the severity of some frontal and side collisions. The SDM uses the input from the impact sensors to determine if air bag deployment is necessary. If the SDM determines a deployment is warranted, the SDM will cause current to flow through the deployment loops deploying the frontal air bags.

SIR SYSTEM DESCRIPTION AND OPERATION

The inflatable restraint sensing and diagnostic module (SDM) stores a primary data key, which is a 4-digit number. When the ignition is turned ON, the SDM compares this information to the information stored in the body control module (BCM) via serial data communication. If there is a mismatch between the information stored in the SDM and BCM, DTC B1001 will set.

SIR SYSTEM DESCRIPTION AND OPERATION

Inflatable restraint sensing and diagnostic module (SDM) monitors the number of safety components that have been installed on the vehicle. When the ignition is turned ON, the SDM evaluates the number of safety components installed and compares it to the number of components the SDM expects to see on the vehicle with its current calibration. If there is a mismatch between detected components and the components programmed with the SDM calibration, DTC B1019 will set. The components (if equipped) that the SDM will detect include inflatable restraint deployment loops, impact sensors, passenger presence system components, seat position sensors, disable switches, and seat belt switches.

1. «SEAT BELT SYSTEM DESCRIPTION AND OPERATION»(ref-652266-S33651531802014082300000)
2. «SIR SYSTEM DESCRIPTION AND OPERATION»(ref-652256-S29569108942014082300000)

When the ignition is turned ON, during the bulb check, the driver air bag indicator will flash, and then turn OFF after the bulb check. The inflatable restraint sensing and diagnostic module (SDM) performs diagnostic tests on the SIR system during the bulb check. If any malfunction exists the SDM will request the instrument cluster to illuminate the air bag indicator steady, via serial data. If a previous malfunction exists, the air bag indicator will illuminate steadily immediately after the ignition is turned ON. If the ignition 1 voltage is outside of the normal operating voltage range of 9-16 V, the SDM will command the instrument cluster to illuminate the air bag indicator, even with no DTCs present, and then disable all deployment loops.

SIR SYSTEM DESCRIPTION AND OPERATION

Circuit/System Description (C99)

When the ignition switch is turned to ON, the inflatable restraint sensing and diagnostic module (SDM) continuously checks the air bag enable/disable switch position switch and circuit defect by letting regular voltage flow through the switch circuit and verifying the current. The passenger air bag switch controls when the air bag is enabled or disabled and notifies the driver when the passenger instrument panel air bag is enabled or disabled using the passenger air bag ON/OFF indicators. When the SDM receives the signal from the passenger air bag disable switch (on/off), the SDM will then provide voltage to the appropriate indicator.

Circuit/System Description (ALO)

The passenger air bag ON/OFF indicators are used to notify the driver when the passenger presence system has enabled or disabled the passenger instrument panel air bag. When the ignition is turned ON, the ignition voltage is supplied to the passenger presence module. When the SDM receives the appropriate serial data message from the passenger presence system the SDM will then provide voltage to the appropriate indicator.

SIR SYSTEM DESCRIPTION AND OPERATION