Air Bag and Safety Belt Pretensioner 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) 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 advantages of the SRS.

The air bag and safety belt pretensioner 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 signal from the Restraints Control Module (RCM).
^ 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 installed as an assembly.
^ is mounted in the passenger side of the instrument panel.

Safety Belt Pretensioners
As part of the supplemental restraint system (SRS), the vehicle is equipped with one of two types of safety belt pretensioners. The pretensioners are activated by the restraints control module (RCM) when the module detects a crash event force exceeding a programmed limit.

Safety Belt Retractor Pretensioners
Vehicle not equipped with Seat Integrated Restraints (SIR), the safety belt retractors are equipped with pretensioners. The belt retractor pretensioners rotate the safety belt retractors to remove excess slack from the safety belt webbing.

Safety Belt Buckle Pretensioners
Vehicle equipped with seat integrated restraints (SIR), the safety belt buckles are equipped with pretensioners. The safety belt buckle pretensioners remove excess slack from the safety belt webbing.

Passenger Air Bag Deactivation (PAD) Switch
The Passenger Air Bag Deactivation (PAD) switch:
^ is present on regular cab and SuperCab vehicles only.
^ is located on the instrument panel to the right of the climate controls.
^ contains a Light Emitting Diode (LED) that indicates when the PAD switch is activated (passenger 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.

Restraints Control Module (RCM)
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 retractor 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 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 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 from 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 RIGHT COWL A-PILLAR 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 contains two sensors which are integral to the RCM. The RCM is mounted on the center tunnel under the instrument panel.