Contents: Airbag modules ⤓ Sensor block/diagnostic module ⤓ Precautionary measures ⤓ Disabling the SRS system ⤓ SRS activation ⤓
Some of the models discussed in this manual are equipped with a supplemental restraint system (SRS), better known as an airbag. The system provides additional protection for the driver and, if equipped, the front passenger of the vehicle in the event of a severe frontal impact. Early models are equipped with only a driver's airbag, the module of which is located inside the hub portion of the steering wheel assembly. The passenger airbag module is located under the right-hand instrument panel of the vehicle, on the surface of which a warning inscription in the form of an abbreviation SRS is applied. The sensor unit/diagnostic module is also located under the instrument panel, in its central part. Directional G-sensors are usually mounted in the front part of the vehicle body.
Airbag modules
The airbag(s) are activated when the SRS directional overload sensors are triggered. Closing the airbag module circuit causes the airbag to fill almost instantly with nitrogen released by the combustion of a powder mixture of sodium azide and copper oxide. If the on-board battery fails, the system switches to power from a backup source built into the SRS module. It should be noted that the passenger airbag is usually larger in volume than the driver's airbag and is equipped with a metal supporting body that splits into two halves when the module is triggered, and a trim cover.
Sensor block/diagnostic module
The SRS sensor and self-diagnostic module supplies power to the airbag modules at the moment of a collision that causes sufficiently strong directional overloads. The system is triggered even in the event of an emergency failure of the on-board storage battery. The module polls the state of the SRS components each time the engine is started and is accompanied by a short-term activation of the "AIR BAG"/SRS indicator lamp built into the vehicle's instrument panel. In the event of failure of any of the components, the indicator lamp does not turn off. A malfunction in the system is also indicated by the indicator lamp triggering while driving - the vehicle should be driven to a service station as soon as possible.
Precautionary measures
Special precautions must be taken when removing or servicing components of the steering column, radio, and other components located near the instrument panel, as accidental damage to the SRS wiring may result in unauthorized deployment of the airbags, which could result in serious injury. The SRS wiring is easily identified by its bright yellow insulation - do not disconnect its connectors or connect any electrical diagnostic equipment to them under any circumstances.
Warning! Before performing any work near SRS components, be sure to turn off the system!
Once the airbag module has been removed from the vehicle, hold it with the front side facing away from you - move the assembly to a safe place and place it with the front side facing up.
Do not attempt to measure the resistance of SRS components under any circumstances - the energy generated by the ohmmeter's internal power source may be sufficient to trigger the gas generators!
Before using any electronic equipment on the vehicle, it is essential to disable the SRS (see below).
Never dispose of airbag modules that have never deployed in the waste bin - advice on disposal of SRS components is always available at service stations.
Disabling the SRS system
To disable the airbags, perform the following manipulations:
- a) Set the vehicle's steering wheels to the straight-ahead position, turn the ignition key to the LOCK position and remove it from the lock;
- b) Disconnect the negative battery cable.
Warning! If the car stereo system is equipped with a security code, make sure you have the correct combination to activate the audio system before disconnecting the battery!
- c) Before performing any work, wait at least 60 seconds to allow the SRS backup power supply capacitor to discharge.
SRS activation
To activate the system, connect the negative cable to the battery, turn the ignition key to the position and check that the SRS indicator lamp operates properly.