Description (SRS-Type III)

The SRS is a safety device which, when used in conjunction with the seat belt, is designed to help protect the driver and front passenger in a frontal impact exceeding a certain set limit. The system consists of the SRS unit (including safing sensor and impact sensor), the cable reel and driver's airbag, and front passenger's airbag.

Operation

The main circuit in the SRS unit senses and judges the force of impact and, if necessary, ignites the inflator charges. If battery voltage is too low or power is disconnected due to the impact, the back-up power circuit will keep voltage at a constant level.

For the SRS to operate:

(1) The impact sensor and safing sensor must activate, and send electric signals to the microprocessor. (2) The microprocessor must compute the signals, and must send signals to the airbag inflators. (3) The inflators must ignite and deploy the airbags.

Self-diagnosis System

A self-diagnosis circuit is built into the SRS unit; when the ignition switch is turned ON (II), the SRS indicator light comes on and goes off after about six seconds if the system is operating normally. If the light does not come on, or does not go off after six seconds, or if it comes on while driving, it indicates an abnormality in the system. In case there is a system abnormality immediately after the ignition switch has been turned ON (II), the reconstruction circuit prevents malfunction. The system must be inspected and repaired as soon as possible.

For better serviceability, the memory will store the cause of the malfunction, and the data link circuit passes on the information from the memory to the data link connector.