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8. Continued See Figure 46–2 for an example of an inertia-type seat belt locking mechanism. Safety Belt Lights and Chimes All late-model vehicles are equipped with a safety belt warning light on the dash and a chime that sounds if the belt is not fastened. See Figure 46–3. Some vehicles will intermittently flash the reminder light and sound a chime until the driver and sometimes the front passenger fasten their safety belts.

9. Figure 46–2 Most safety belts have an inertia-type mechanism that locks the belt in the event of rapid movement. Figure 46–3 A typical safety belt warning light.

11. Figure 46–4 A small explosive charge forces the end of the seat belt down the tube, which removes any slack in the seat belt. CAUTION: The seat belt pretensioner assemblies must be replaced in the event of an airbag deployment. Always follow the vehicle manufacturer’s recommended service procedure. Pretensioners are explosive devices that could be ignited if voltage is applied to the terminals. Do not use a jumper wire or powered test light around the wiring near the seat belt latch wiring. Always follow the vehicle manufacturer’s recommended test procedures.

16. Figure 46–7 Lifting the squib from the airbag housing. The squib is the heating element that ignites the pyrotechnic gas generator that rapidly produces nitrogen gas to fill the airbag. Figure 46–8 This shows a deployed side-curtain airbag on a training vehicle. Continued

19. Figure 46–9 An airbag magnetic sensor. Continued Figure 46–10 Some vehicles use a ribbon-type crash sensor.

21. Figure 46–11 Notice that within 1/4 second of a collision, the sensors have closed, the airbag has deployed, and the airbag has deflated. Continued

23. Figure 46–12 The airbag control module is linked to the power train control module (PCM) and the body control module (BCM) on this DaimlerChrysler system. Notice the airbag wire connecting the module to the airbag through the clockspring. Continued

25. Figure 46–14 An airbag diagnostic tester. Included in the plastic box are electrical connectors and a load tool that substitutes for the inflator module during troubleshooting. Figure 46–13 An airbag being deployed as part of a demonstration in an automotive laboratory. Continued

27. When replacing any steering gear such as a rack-and-pinion steering unit, be sure that no one accidentally turns the steering wheel. If the steering wheel is turned without being connected to the steering gear, the airbag wire coil (clock-spring) can become off center. This can cause the wiring to break when the steering wheel is rotated after the steering gear has been replaced. To help prevent this from occurring, simply remove the ignition key from the ignition and keep it in your pocket while servicing the steering gear. Pocket the Ignition Key to be Safe

36. Figure 46–15 This figure shows the process of removing the airbag inflator module from the steering wheel and disconnecting the yellow airbag electrical connector. Figure 46–16 Shorting bars are used in most airbag connectors. These spring-loaded clips short across both terminals of an airbag connector to help prevent accidental deployment of the airbag. If electrical power was applied to the terminals, the shorting bars would simply provide a low-resistance path to the other terminal and not allow current to flow past the connector. The mating part of the connector has a tapered piece that spreads apart the shorting bars. Continued

43. Figure 46–19 A resistor-type occupant detection sensor. The weight of the passenger strains these resistors, which are attached to the seat, thereby signaling to the module the weight of the occupant. CAUTION: Because resistors are part of the seat structure, it is very important that all seat fasteners be torqued to factory specs to ensure proper operation of the occupant detection system. A seat track position sensor is used by the airbag controller to determine the seat position. If the seat is too close to the airbag, the controller may disable the airbag. Continued

50. If a vehicle equipped with the OnStar system is being driven aggressively and the electronic stability control system has to intercede to keep the vehicle under control, OnStar may call the vehicle to see if there has been an accident. The need for a call from OnStar usually will be determined if the accelerometer registers slightly over one-g of force, which could be achieved while driving on a race track. Aggressive Driving and OnStar ® ® ® ®

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