Scheme 25
Each airbag module consists of an inflatable bag and a gas generator. These are mounted as one unit in the center of the steering wheel and in the dashboard.
| WARNING | Airbag modules must never be disassembled, repaired or transferred to another vehicle. |
If the car is to be scrapped or the airbag replaced, see Handling non-deployed airbag modules/pyrotechnic seat-belt tensioners .
Note. Volvo recommends that airbag modules be replaced every 10 years to maintain reliability.
Scheme 26
The steering wheel module consists of an electrical igniter (A) mounted in gas generator (B) which opens into to the folded airbag. When the igniter receives an electrical signal from the sensor module, the gas generator produces a harmless gas which rapidly inflates the airbag.
Scheme 27
The passenger module is constructed in the same way as the steering wheel module, with the distinction that the gas generator is adapted to the greater volume of the airbag.
| WARNING | Never put a child seat on the front passenger seat if the car is equipped with an SRS (Airbag) on the passenger side. |
Scheme 28
Disconnecting the passenger airbag module
The passenger airbag module SRS ignition cable can be disconnected in accordance with the car owner's wishes in markets where this does not conflict with statutory requirements. This makes it possible to place a rear facing child seat on the front passenger seat.
Scheme 29
The airbag is folded on top of the gas generator in the airbag modules. When inflated, the volume of the airbag is approx. 150 liters (40 US gallons) on the passenger side and approx. 60 liters (16 US gallons) on the driver's side.
The airbag is made of heavy duty polyamide fabric with venting holes. The gas escapes through the venting holes so that the airbag collapses at the right speed to arrest the forward movement of the driver and passenger.
Description
The sensor elements detect a combination of G force and duration. To activate the system the sensor module must detect a high G force and prolonged deceleration. The sensor module will not, for example, activate the system after a hammer blow (high G force, short duration).
A collision violently decelerates the car. The sensor module determines whether the collision is sufficiently powerful to activate the system. If this is the case the sensor module activates the gas generators. The airbags are inflated and the seat belts are tensioned.
The sensor module also has a back up power function which stores enough power to allow the system to operate even if battery power is interrupted. This can happen if cabling is trapped or the battery is damaged in a collision. There is power for a maximum of 10 seconds after power is interrupted or the ignition is switched off. This power is enough to trigger all igniters within 100 ms of a collision taking place and battery power being interrupted.
It is important that the sensor module be securely mounted onto the bodywork if the sensor module is to operate properly. Otherwise it will only register its own deceleration, not deceleration from the beginning of the collision. Electrical connection to ground is through the ground terminal which is fixed by one of the mounting screws. It is therefore very important that the mounting screws are in good contact with the bodywork. When installing the stated torque must not be exceeded.
Scheme 30
The SRS system is continuously monitored by the micro processor in the sensor module. If a fault occurs, information about its type and location is stored. At the same time an indicator lamp lights in the combined instrument.
When the ignition is switched to position II, the indicator lamp lights with the other lamps on the panel to confirm that the bulb is working.
When the engine is started the SRS warning lamp goes out, showing that the system is fault free.
If the engine is not started when the ignition is switched to position II, the lamp should go out after approx. ten seconds.
There is a fault if the SRS warning lamp does not go out or lights when the car is being driven.
Scheme 31
Information about faults and other information can be read off using the Volvo Scan Tool (ST) connected to the data link connector (DLC).
The Volvo Scan Tool (ST) communicates with the sensor module through a standardized communications network.
The data link connector (DLC) is located in the center console by the cigarette lighter tray. The data link connector (DLC) is common to Volvo Diagnostics and the statutory diagnostic system OBD II, On Board Diagnostics II (OBD II only certain markets, USA/CDN).
To activate Volvo Diagnostics for the SRS system.
- ignition on
- supply battery voltage.