Part 4
PASSENGER AIRBAG ON/OFF SWITCHA passenger side airbag ON/OFF switch is used on certain models not equipped with factory-installed or approved rear passenger seating. This switch is a single pole, single throw switch with a single integral red Light-Emitting Diode (LED), and a non-coded key cylinder-type actuator. The switch is located in the lower right corner of instrument panel cluster bezel, near the center of instrument panel to make the OFF indicator visible to all front seat occupants. When the switch is in its installed position, the only components visible through the dedicated opening of the cluster bezel are the accessory switch plate and nomenclature, the key cylinder actuator, and a small round lens with the text "OFF" imprinted on it. The "ON" position of the switch is designated by text imprinted upon the accessory switch plate, but is not illuminated. The remainder of the switch is concealed behind the accessory switch plate and the instrument panel cluster bezel.
The passenger airbag ON-OFF switch housing is constructed of molded plastic and has three integral mounting tabs. Two of these mounting tabs are used to secure the switch to the back of the molded plastic accessory switch plate with two small screws, while the third mounting tab is not used in this application. The molded plastic accessory switch plate also has three integral mounting tabs that are used to secure the switch and accessory switch plate unit to the instrument panel with three additional screws. Two short pigtail wires with molded plastic connector insulators exit the back of the switch housing and connect the switch to the vehicle electrical system through two dedicated take outs of the instrument panel wire harness. The harness take outs are equipped with molded plastic connector insulators that are keyed and latched to ensure proper and secure switch electrical connections. The passenger airbag ON/OFF switch cannot be adjusted or repaired and, if faulty or damaged, the switch must be replaced.
The passenger airbag ON/OFF switch allows the customer to turn the passenger airbag function ON or OFF to accommodate certain uses of the right front seating position where airbag protection may not be desired. See the owner's manual in the vehicle glove box for specific recommendations on when to enable or disable the passenger airbag. The OFF indicator of the switch will be illuminated whenever the switch is turned to the OFF position. The ignition key is the only key or object that should ever be inserted into the switch. The ON/OFF switch requires only a partial key insertion to fully depress a spring-loaded locking plunger. The spring-loaded locking plunger prevents the user from leaving the key in the switch. The key will be automatically ejected when force is not applied. To actuate the passenger side airbag ON/OFF switch, insert the ignition key into the switch key actuator far enough to fully depress the plunger and rotate to the desired switch position. When the switch key actuator is rotated to its clockwise stop (the key actuator slot will be aligned with the OFF indicator lamp), the OFF indicator is illuminated and the passenger airbag is disabled. When the switch is rotated to its counterclockwise stop (the key actuator slot will be in a horizontal position), the OFF indicator will be extinguished and the passenger airbag is enabled.
The passenger airbag ON/OFF switch is connected in series between the Airbag Control Module (ACM) and the passenger airbag inflator unit. When the switch is in the ON position, the switch connects the ACM directly to the passenger airbag inflator. When the switch is in the OFF position it interrupts the inflator circuits, but replaces the normal resistance in these circuits with an internal resistor. Thus, the ACM is unable to distinguish the mode of the switch and still sends an electrical signal as though it were deploying the passenger airbag when it detects a sufficient impact. However, the switch position should not be changed while the ignition switch is in the ON position, as the ACM may detect a fault, record a Diagnostic Trouble Code (DTC), and illuminate the Airbag indicator in response to a momentary open it senses in the passenger airbag inflator circuits as the ON/OFF switch changes states.
SEAT BELT SWITCH
The seat belt switch is a small, normally open, single pole, single throw, plunger actuated, momentary switch. Only one seat belt switch is installed in the vehicle, and it is integral to the driver seat belt retractor assembly. The seat belt switch is connected to the vehicle electrical system through a short pigtail wire to a dedicated take out and connector of the body wire harness.
The seat belt switch cannot be adjusted or repaired and, if faulty or damaged, the entire driver seat belt and retractor unit must be replaced.
The seat belt switch is designed to control a path to ground for the seat belt switch sense input of the Electro-Mechanical Instrument Cluster (EMIC). The seat belt switch plunger is actuated by the seat belt webbing wound onto the seat belt retractor spool. When the seat belt tip-half webbing is pulled out of the retractor far enough to engage the seat belt buckle-half, the switch plunger is extended and closes the seat belt switch sense circuit to ground; and, when the seat belt tip-half webbing is wound onto the retractor the switch plunger is depressed, opening the ground path. The EMIC monitors the seat belt switch status, then controls the outputs to the integral seatbelt indicator and chime tone generator.
The seat belt switch receives ground through its pigtail wire connection to the body wire harness from another take out of the body wire harness. An eyelet terminal connector on that ground take out is secured under a ground screw to the left lower B-pillar. The seat belt switch is connected in series between ground and the seat belt switch sense input of the EMIC.
SEAT BELT TENSIONER
Seat belt tensioners supplement the airbag system for all versions of this model. The seat belt tensioners are integral to the front seat belt retractors, which are secured to the B-pillar on the left side of the vehicle, and to the outboard side of the front seat riser on the right side of the vehicle. Each retractor is concealed beneath a molded plastic trim cover. The seat belt tensioner consists primarily of a sprocket/pinion, a steel tube, a cast metal housing, numerous steel balls, a stamped metal ball trap, a torsion bar, a small pyrotechnically activated gas generator, and a short pigtail wire. All of these components are located on one side of the retractor spool on the outside of the retractor housing except for the torsion bar, which serves as the spindle upon which the retractor spool rides. The seat belt tensioners are controlled by the Airbag Control Module (ACM) and are connected to the vehicle electrical system through a dedicated take out of the body wire harness by a keyed and latching molded plastic connector insulator to ensure a secure connection.
The seat belt tensioners cannot be repaired and, if faulty or damaged, the entire front seat belt, retractor, and tensioner unit must be replaced. The seat belt tensioners are not intended for reuse, and both tensioners must be replaced following any airbag deployment. A growing or grinding sound while attempting to operate the seat belt retractor is a sure indication that the seat belt tensioner has been deployed and requires replacement. For seat belt tensioner service procedures, (Refer to RESTRAINTS/FRONT SEAT BELT & RETRACTOR - REMOVAL).
The seat belt tensioners are deployed in conjunction with the airbags by a signal generated by the Airbag Control Module (ACM) through the driver or passenger seat belt tensioner line 1 and line 2 (or squib) circuits. When the ACM sends the proper electrical signal to the tensioner, the electrical energy generates enough heat to initiate a small pyrotechnic gas generator. The gas generator is installed in one end of a steel tube that contains numerous steel balls. As the gas expands, it pushes the steel balls through the tube into a cast metal housing, where a ball guide directs the balls into engagement with the teeth of a sprocket that is geared to one end of the retractor spool. As the balls drive past the sprocket, the sprocket turns and drives the seat belt retractor spool causing the slack to be removed from the front seat belts. The ball trap captures the balls as they leave the sprocket and are expelled from the housing. Removing excess slack from the front seat belts not only keeps the occupants properly positioned for an airbag deployment following a frontal impact of the vehicle, but also helps to reduce the likelihood of a harmful contact with interior components. Also, the seat belt tensioner torsion bar that the retractor spool rides upon is designed to deform in order to control the loading being applied to the occupants by the seat belts during a frontal impact, further reducing the potential for occupant injuries.
The ACM monitors the condition of the seat belt tensioners through circuit resistance, and will illuminate the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) and store a Diagnostic Trouble Code (DTC) for any fault that is detected. For proper diagnosis of the seat belt tensioners, a DRB III scan tool is required. Refer to the appropriate diagnostic information.