Theory Of Operation
A Supplemental Restraint System (SRS) is standard factory-installed safety equipment on this vehicle. Available supplemental occupant restraints for this vehicle include both Active and Passive types. Active restraints are those which require the vehicle occupants to take some action to employ, such as fastening and adjusting a seat belt; while passive restraints require no action by the vehicle occupants to be employed.
The Occupant Restraint Controller (ORC) and the Instrument Panel Cluster (IPC) each contain a microcontroller and programming that allow them to communicate with each other using the Controller Area Network (CAN) data bus. This method of communication is used by the ORC for control of the airbag indicator in the IPC.
ACTIVE RESTRAINTS
The primary passenger restraints in this vehicle are the standard equipment factory-installed seat belts and child restraint anchors. Seat belts and child restraint anchors are referred to as an active restraint because the vehicle occupants are required to physically fasten and properly adjust these restraints in order to benefit from them.
The seat belt retractors may include an inertia-type, emergency locking mechanism as standard equipment. Seat belt retractors with a locking mechanism are capable of mechanically changing from an Emergency Locking Retractor (ELR) to an Automatic Locking Retractor (ALR). The primary function of this feature is to securely accommodate a child seat in the vehicle without the need for a self-cinching seat belt tip half latch plate unit or another supplemental device that would be required to prevent the seat belt webbing from unwinding freely from the retractor spool of an inertia-type emergency locking retractor mechanism. Refer to the Owners Manual Information for a more in-depth location and functionality of ELR/ALR Seatbelts located in the Safety Section.
The emergency and automatic locking mechanisms are integral to the seat belt and retractor unit and are concealed beneath a molded plastic cover located on one side of the retractor spool. These locking mechanisms cannot be adjusted or repaired and, if ineffective or damaged, the entire seat belt and retractor unit must be replaced. For more information on the seat belts in this vehicle, refer to the Safety Section in the Owners Manual.
PASSIVE RESTRAINTS
The passive restraints are referred to as a SRS components because they were designed and are intended to enhance the protection for the occupants of the vehicle only when used in conjunction with the seat belts. They are referred to as passive restraints because the vehicle occupants are not required to do anything to make them operate; however, the vehicle occupants must be wearing their seat belts in order to obtain the maximum safety benefit from the factory-installed SRS components.
The SRS electrical circuits are continuously monitored and controlled by a microcontroller and software contained within the ORC. An airbag indicator in the IPC illuminates from four to six seconds as a bulb test each time the status of the ignition transitions to ON or START. Following the bulb test, the airbag indicator is turned ON or OFF by the ORC to indicate the status of the SRS. If the airbag indicator comes ON at any time other than during the bulb test, it indicates that there is a problem in the SRS electrical circuits. Such a problem may cause airbags not to deploy when required, or to deploy when not required.
For additional information regarding the description and operation of the Restraints System, Refer to DESCRIPTION AND OPERATION .