General Precautions
The SRS system contains components which could be potentially hazardous to the service engineer if not serviced and handled correctly. The following guidelines are intended to alert the service engineer to potential sources of danger and emphasize the importance of ensuring the integrity of SRS components fitted to the vehicle.
It should be noted that these precautions are not restricted to operations performed when servicing the SRS system, the same care should be exercised when working on ancillary systems and components located in the vicinity of the SRS components; these include but are not limited to:
- Steering system - (steering wheel airbag)
- Body and trim components - (passenger airbag, seatbelt pre-tensioners and SRS DCU).
- Seats - (side airbags)
- Electrical system components - (SRS harnesses etc.)
WARNING: Do not use rear facing child seats in the front passenger seat when a vehicle is fitted with a front passenger airbag.
WARNING: Always follow the Safety Guidelines and correct procedures for working on SRS components.
WARNING: The front airbag modules contain Sodium Azide which is poisonous and extremely flammable. Contact with water, acid or heavy metals may produce harmful or explosive compounds. Do not dismantle, incinerate or bring into contact with electricity.
CAUTION: Do not expose an airbag module or seatbelt pre-tensioner to heat exceeding 85° C (185° F).
NOTE: Front airbag modules should be replaced every ten years; side airbag modules should be replaced every fifteen years.
Making the system safe
Before working on, or in the vicinity of SRS components, ensure the system is rendered safe by performing the following procedures:
- Remove the ignition key from the ignition switch.
- Disconnect both battery leads, earth lead first.
- Wait 10 minutes for the SRS DCU back-up power circuit to discharge.
The SRS system uses energy reserve capacitors to keep the system active in the event of electrical supply failure under crash conditions. It is necessary to allow the capacitor sufficient time to discharge (10 minutes) in order to avoid the risk of accidental deployment.
WARNING: Always remove the ignition key from the ignition switch, disconnect the vehicle battery and wait 10 minutes before commencing work on the SRS system.
CAUTION: Always disconnect both battery leads before beginning work on the SRS system. Disconnect the negative battery cable first. Never reverse connect the vehicle battery and always ensure the correct polarity when connecting test equipment.
CAUTION: Always disconnect the vehicle battery before carrying out any electric welding on a vehicle fitted with an SRS system.
Installation
WARNING: Always follow the safety guidelines and correct procedures for working on SRS components. Persons working on SRS systems must be fully trained and have been issued with copies of the Safety I Manufacturing guidelines.
In order to assure system integrity, it is essential that the SRS system is regularly checked and maintained so that it is ready for effective operation in the event of a collision. Carefully inspect SRS components before installation. Do not install a part that shows signs of being dropped or improperly handled, such as dents, cracks or deformation.
CAUTION: Ensure SRS components are not contaminated with oil, grease, detergent or water.
CAUTION: It is essential that SRS components are fitted using the recommended torques, and always use new fixings when replacing SRS parts. Special bolts are necessary for installing the airbag module, do not use other bolts.
CAUTION: Never attempt to repair an SRS component. Do not try to dismantle an airbag module, there are no serviceable parts. Once an airbag or pre-tensioner has been deployed, it cannot be repaired or re-used.
CAUTION: Do not install used SRS components from another vehicle. When repairing an SRS system, only use genuine new parts.
CAUTION: Ensure the SRS DCU and front crash sensors (if fitted) are installed correctly. There must not be any gap between the component and the bracket to which it is mounted. An incorrectly mounted unit could cause the system to malfunction.
WARNING: When removing, testing or installing an airbag module, do not lean directly over it.
WARNING: Never use multimeters or other general purpose test equipment to check SRS components or connectors. System faults should be diagnosed through the use of recommended test equipment only.
WARNING: Never apply electrical power to an SRS component unless instructed to do so as part of an approved test procedure.
CAUTION: Prior to commencing any test procedure on the vehicle, ensure that only test equipment approved for the purpose is being utilized and that it is in good working order. Ensure any harness or connectors are in good condition and any warning lamps are fully functional.
Handling And Storage:
WARNING: The SRS components are sensitive and potentially hazardous if not handled correctly; always comply with the following handling precautions:
- Never drop an SRS component. The airbag diagnostic control unit is a particularly shock sensitive device and must be handled with extreme care. Airbag modules and seatbelt pre-tensioner units could deploy if subjected to a strong shock.
- Never wrap your arms around an airbag module. If it has to be carried, hold it by the cover with the cover uppermost and the base away from your body.
- Never transport airbag modules or seatbelt pre-tensioners in the cabin of a vehicle. Always use the luggage compartment of the vehicle for carrying airbag modules and seatbelt pre-tensioner units.
- Never attach anything to the airbag cover or allow anything to rest on top of the airbag module.
- Always keep components cool, dry and free from contamination.
WARNING: Always store airbag modules with the cover face up. If the airbag module is stored face down, accidental deployment could propel the unit with enough force to cause serious injury.
WARNING: Airbag modules and seatbelt pre-tensioners are classed as explosive devices. For overnight and longer term storage, they must be stored in a secure steel cabinet which has been approved as suitable for the purpose and has been registered by the local authority.
CAUTION: For the temporary storage of an airbag or seatbelt pre-tensioner during service, place in a designated storage area. If there is no designated storage area available, store in the luggage compartment of the vehicle and inform the workshop supervisor.
CAUTION: Improper handling or storage can internally damage the airbag module, making it inoperative. If you suspect the airbag module has been damaged, install a new unit and refer to the Deployment/Disposal Procedures for disposal of the damaged airbag.
CAUTION: Always observe the following precautions with regards to SRS system electrical wiring:
- Never attempt to modify, splice or repair SRS wiring.
- Never install electronic equipment (such as a mobile telephone, two-way radio or in-car entertainment system) in such a way that it could generate electrical interference in the airbag harness. Seek specialist advice when installing such equipment.
NOTE: SRS system wiring can be identified by a special yellow outer sleeve protecting the wires (black with yellow stripe protective coverings are sometimes used).
CAUTION: Always use specified earth fixings tightened to the correct torque. Poor earthing can cause intermittent problems that are difficult to diagnose.
CAUTION: Always ensure airbag wiring is routed correctly. Be careful to avoid trapping or pinching the airbag wiring. Look for possible points of chafing.
CAUTION: Ensure all airbag harness connectors are mated correctly and securely fastened. Do not leave the connectors hanging loose or allow SRS components to hang from their harnesses.