General

RESTRAINT SYSTEMS

75-4

DESCRIPTION AND OPERATION

Description

General
The Supplementary Restraint System (SRS) provides additional protection for front seat occupants during a frontal 
collision above a preset severity. The SRS is an electronically controlled, single point sensing system. The system 
comprises:

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An airbag Diagnostic Control Unit (DCU).

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A driver's airbag module.

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A front passenger's airbag module.

NOTE: In some markets an optional stowage bin is installed in place of the front passenger's airbag module.

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Two front seat belt pretensioners.

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A warning lamp.

Impact Zone for SRS Activation (Approximate)

Interconnecting wiring for the system is integrated into the vehicle harnesses. A rotary coupler connects the vehicle 
harness to the driver's airbag module. An ISO 9141 K line (bi-directional) serial communication link connects the 
airbag DCU to the vehicle's diagnostic socket.

The system is operational only while the ignition is on. With the ignition on, any frontal collision is detected by the 
airbag DCU. If the impact is above the preset severity, the DCU sends out simultaneous fire signals to the airbag 
modules and the seat belt pretensioners. The airbag modules then deploy protective airbags in front of the driver and 
front  seat passenger, and the seat belt pretensioners retract to tighten the front seat belts. Collision detection to full 
deployment of the airbags and pretensioners takes approximately 45 milliseconds.