System Diagram
- Power supply circuit (booster circuit, backup power supply): Provided to maintain power when battery voltage is low or in case of power supply damage due to a collision.
- Front impact G sensor and side impact G sensor: Detect impact to the SRS unit as acceleration and convert it to electrical signal.
- Rollover judgment circuit: Predicts an impending rollover using signals such as the one from the G sensor located inside of the SRS unit. Based on the rollover judgment and the seat belt buckle switch status, the circuit determines whether the side airbags and the side curtain airbags should deploy or not.
- Microprocessor: An impact decision algorithm decides whether or not the collision signal warrants deployment of the airbags or the tensioners.
- Diagnostic circuit: Performs self-diagnosis to determine whether system abnormalities are present. If an abnormality is detected, the SRS indicator in the gauge control module turns on.
- Non-volatile memory: Records fault conditions. The SRS memories are not erased even if the 12 volt battery terminal is disconnected.
- Communication circuit: Circuit for outputting or deleting memory contents.
When airbags or tensioners are about to be deployed, a large amount of current passes through the SRS unit. After the airbags and tensioners are deployed, the internal components of the SRS unit are damaged, and must be replaced.