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 voltage regulator and the back-up power circuit will keep voltage at a constant level.

(1) A front impact sensor or the side impact sensor must activate and send electric signals to the microprocessor.

(2) The microprocessor must compute the signals and send them to the tensioners.

(3) The charges must ignite and deploy the tensioners.

(1) A front impact sensor must activate, and send electric signals to the microprocessor.

(2) The microprocessor must compute the signals, and send them to the airbag inflator(s).

(3) The inflators that received signals must ignite and deploy the airbags.

(1) A side impact sensor must activate, and send electric signals to the microprocessor.

(2) The microprocessor must compute the signals and send them to the side airbag inflator(s). However, the microprocessor cuts off the signals to the front passenger's side airbag if the SRS unit determines that the front passenger's head is in the deployment path of the side airbag.

(3) The inflator that receives the signal must ignite and deploy the side airbag.

A self-diagnostic circuit is built into the SRS unit; when the ignition switch is turned to ON (II), the SRS indicator comes on and goes off after about 6 seconds if the system is operating normally. If the indicator does not come on, or does not go off after 6 seconds, or if it comes on while driving, it indicates an abnormality in the system. The system must be inspected and repaired as soon as possible.

For better serviceability, the SRS unit memory stores a DTC that relates to the cause of the malfunction, and the unit is connected to the data link connector (DLC). This information can be read with the HDS when it is connected to the DLC (16P).

NOTE: Before you disconnect the negative cable from the battery for troubleshooting, make sure you have the anti-theft codes for the audio system and the navigation system (if equipped).