Air Bag/Safety Belt Pretensioner Supplemental Restraint System

AIR BAG AND SAFETY BELT PRETENSIONER SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

The air bag supplemental restraint system (SRS) is designed to provide increased collision protection for front seat occupants in addition to that provided by the three-point safety belt system. Safety belt use is necessary to obtain the best occupant protection and to receive the full advantage of the SRS.

Air Bag And Safety Belt Pretensioner Supplemental Restraint System (SRS) Components, Part 1:

Air Bag And Safety Belt Pretensioner Supplemental Restraint System (SRS) Components, Part 2:

The air bag supplemental restraint system (SRS) components are shown in the illustration.

Driver Air Bag Module
The driver air bag module:
- is steering wheel mounted.
- will deploy upon receiving a flow of current from the restraints control module (RCM).
- is installed as an assembly.
- has no subassemblies.

Clockspring
The clockspring:
- is mounted on the steering column, behind the steering wheel.
- provides a continuous electrical path from the driver air bag module to the restraints control module (RCM).

Passenger Air Bag Module
The passenger air bag module:
- is mounted in the passenger side of the instrument panel.
- will deploy upon receiving a flow of current from the restraints control module (RCM).
- is installed as an assembly.
- has no subassemblies.

Passenger Air Bag Deactivation (PAD) Switch
The passenger air bag deactivation (PAD) switch:
- is located on the LH side of the instrument panel ash receptacle.
- contains a light emitting diode (LED) that indicates when the PAD switch is activated (air bag disabled).
- allows the passenger air bag deployment circuit to be disabled using the ignition key.
- should be used whenever a child safety seat is being used in the front passenger seating position.

Safety Belt Pretensioners

NOTE: There is no restraint system diagnostic tool for the safety belt buckle pretensioners. If the ignition switch is turned to the RUN or START position with the safety belt buckle pretensioner electrical connector(s) disconnected, the DTC for an open circuit will be activated.

As part of the supplemental restraint system (SRS), the safety belt buckles are equipped with pretensioners. The safety belt buckle pretensioners remove excess slack from the safety belt webbing. The pretensioners are activated by the restraints control module (RCM) when the module detects a frontal impact event exceeding a programmed limit and the safety belt is buckled. The passenger safety belt pretensioner can deploy regardless of the passenger air bag deactivation (PAD) switch setting or the presence of an occupant if the front outboard passenger safety belt is buckled.

Restraints Control Module (RCM)

WARNING: The restraints control module (RCM) orientation is critical for correct air bag supplemental restraint system (SRS) operation. If a vehicle equipped with an SRS system has been involved in a collision in which the center tunnel area has been damaged, inspect the mounting and bracket for deformation. If damaged, the RCM must be replaced whether or not the air bags have deployed. In addition, make sure the area of the RCM mounting is restored to its original condition.

NOTE: When installing a new restraints control module (RCM), always make sure the correct RCM is being installed. If an incorrect RCM is installed, erroneous DTCs will result.

The restraints control module (RCM) is mounted on the center tunnel under the instrument panel. The RCM performs the following functions:
- signals the inflators to deploy the air bags in the event of a deployable crash.
- activates the safety belt buckle pretensioners to remove slack from the safety belt.
- monitors the air bag supplemental restraint system (SRS) for faults.
- illuminates the air bag indicator if a fault is detected.
- flashes the air bag indicator to indicate the lamp fault code (LFC) detected.
- communicates through the data link connector (DLC) the current or historical diagnostic trouble codes (DTCs).
- signals the instrument cluster module to activate a chime if the air bag indicator is not available and another SRS fault exists.
- contains an internal safing sensor which is not serviced separately.

The RCM monitors the SRS for possible faults. If a fault is detected while the ignition switch is in the RUN position, the RCM will illuminate the air bag indicator located in the instrument cluster.

When the ignition is cycled (turned off and then on), the air bag indicator will remain lit for six seconds and then go out. If an SRS fault exists, the air bag indicator will then flash the two-digit LFC. The air bag indicator will flash the LFC five times, then it will remain illuminated for the rest of the key cycle. The RCM will also communicate the current and historical DTCs through the data link connector (DLC), using the scan tool. If the air bag indicator does not function, and the system detects a fault condition, the RCM will signal the instrument cluster module to activate an audible chime. The chime is a series of five sets of five tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.

LFCs are prioritized. If two or more faults occur at the same time, the fault having the highest priority will be displayed first. After that fault has been corrected, the next highest priority fault will be displayed.

The RCM includes a backup power supply. This feature provides sufficient backup power to deploy the air bags in the event that the ignition circuit is damaged in a collision before the safing and air bag sensors determine that an air bag deployment is required. The backup power supply will deplete its stored energy approximately one minute after the battery ground cable is disconnected.

Electrical System
The electrical system that supports the air bag supplemental restraint system (SRS):
- is powered by the battery through the ignition circuit.
- provides the electrical path from the restraints control module (RCM) to the SRS components.
- provides the electrical path from the RCM to the air bag indicator.
- provides the electrical path from the RCM to the data link connector (DLC).
- provides the electrical path from the RCM to the instrument cluster.

Impact Sensors

WARNING: The restraints control module (RCM) orientation is critical for correct system operation. If a vehicle equipped with an air bag supplemental restraint system (SRS) has been involved in a collision in which the center tunnel area has been damaged, inspect the mounting and bracket for deformation. If damaged, the RCM must be replaced whether or not the air bags have deployed. In addition, make sure the area of the RCM mounting is restored to its original condition.

For this vehicle, the SRS employs two impact sensors which are integral to the RCM and are not separately serviceable. The RCM is mounted on the center tunnel under the instrument panel. Mounting orientation is critical for correct operation of all impact sensors.