The earlier models are equipped with a Supplemental Inflatable System (SIR) often referred to as an airbag that is responsible for the safety of the driver and, in some models, the front seat passenger in case of an accident that occurs at the head-on or frontal zone. This system consists of an air bag module mounted at the center of the steering wheel and the right side of the instrument panel, two crash sensors located at the front and the interior of the car, and diagnostic monitor with a backup power source in the passenger compartment. The centre of the operations is the inflator module, which can be clipped on the steering wheel, housing an elongated metal inflator component which inflates the bag within near split seconds, after receiving an electrical signal. A coil assembly on the steering column does so, irrespective of the position of the steering wheel. The Supplemental Restraint (SRS) air bag designed to be mounted on the instrument panel above the glove compartment, it has inflator, bag assembly, reaction housing and trim cover. Other options also comprise the curtain airbags that are in the outer side of the front running board and the seat-belt pre-tensions that help tighten the belts in the case of a major crash. There are three sensors for operation in the remote case, or five ones in the cars with side airbags, which determine adequate G forces and send signals to the electronic diagnostic monitor or Restraints Control Module to launch the airbags. The electronic diagnostic monitor also monitors the airbag system by testing it each time the vehicle is started, and the 'AIR BAG' light will, therefore, light up if it is working correctly. If a fault is detected the J3004S will leave the light on or continually flash which will indicate that it requires servicing. When one needs to work on the airbag related parts some precautions that vary with the manufacturer and the model year of the car need to be taken such as turning off the ignition, disconnecting the battery and removing specified fuses. To enable the system, the battery cables must be connected in the right sequence with the Ignition off.