AIRBAG SYSTEM DETAILS AIRBAG ECU ASSEMBLY

  1. CONSTRUCTION

    1. The airbag sensor assembly consists of judgment circuits, a deceleration sensor, ignition control circuit, safing sensor, backup power circuit, diagnostic circuit and memory circuit.

      Item

      Outline

      Judgment Circuit

      Judgment circuits are built into the airbag sensor assembly to judge the severity of a collision using the acceleration/deceleration signals from the front airbag sensor, side airbag sensor assemblies*1 and side No. 2 airbag sensor assemblies*2.

      Deceleration Sensor

      A deceleration sensor is built into the airbag sensor assembly. This sensor distorts in the event of a collision. The amount of distortion is based on the deceleration rate of the vehicle during a frontal collision and is converted into an electric signal.

      Ignition Control Circuit

      The ignition control circuit performs calculations based on the signal output from the judgment circuit of the airbag sensor assembly, front airbag sensor, side airbag sensor assemblies*1 and side No. 2 airbag sensor assemblies*2. If the calculated values are greater than the specified values, the airbags are deployed.

      Safing Sensor

      During a frontal, side*1 or rear side*2 collision, this sensor turns on and outputs an on signal to the airbag sensor assembly if the deceleration rate of the safing sensor is greater than a specified value.

      Backup Power Circuit

      The backup power circuit consists of a power supply capacitor and a DC-DC converter. When the power supply to the airbag sensor assembly is disrupted during a collision, the power supply capacitor discharges and supplies electric power to the system. The DC-DC converter operates as a boosting transformer when the battery voltage falls below a predetermined level.

      Diagnostic Circuit

      The diagnostic circuit constantly monitors for system malfunctions. When a malfunction is detected, it turns on the SRS warning light in the combination meter assembly to inform the driver.

      Memory Circuit

      When a malfunction is detected by the diagnostic circuit, a DTC is stored in memory.

      *1: Models with front side airbags

      *2: Models with curtain shield airbags