A Supplemental Restraint System (SRS), commonly called air bags, are used on all models to protect the driver and frount seat passenger from serious injury from head on or frontal impact; the crash sensors are behind the front bumper, and are part of the airbag assemblies mounted in the steering wheel and inside the frount passenger's dashboard. Some models have side-impact airbags, with sensors in seat backs in front of the occupants, and in the rear doors on four door models, while others have side curtain airbags hidden behind the headliner. The inflator assembly is contained in the steering wheel along with the driver's side airbag inflator module. An electrical signal from the SRS unit then triggers the inflator assembly, launching the airbag almost instantly. Above the glove box, the passenger's side airbag is larger than the driver's, and deploys through a trim cover that separates to open. It power the airbag system, checks the system at vehicle start from power on, and any faults trips the Srs light to indicate immediate service. Before you work on the steering wheel or dashboard, you want to disarm the system first by straightening the wheels, flip the key to LOCK and remove the negative battery terminal while waiting three minutes. Whenever you are dealing with an airbag module make sure that you take care enough not to put it on cushions with the airbag opening facing down. SRS components may not be electrically tested, and welding equipment may not be used unless airbag connectors are disconnected (easily identifiable by bright yellow color). Airbag modules or seat belt pre-tensioners that are damaged in a crash causing them to live must be returned to a dealer or qualified repair shop for safe disposal. Furthermore, all of the models have pyrotechnic units in the front seat belt retractor that activates in the event of an impact to eliminate slack in the seat belts and prime occupants for a collision; and the airbag system should be disabled when making work around the seats.