2001 > 1.8L DOHC >
Description and operation
Air Bag-Supplemental restraint system
Air Bag-Supplemental Restrain System (SRS) is designed to supplement driver seat belts during front end
collisions, reducing risk of serious injury or death.
Two collision-sensitive sensors are located in Air bag Diagnostic Unit (ADU). These two sensors (Safing sensor
and G-sensor) are electrically connected in series with air bag and battery.
In case of the frontal crash, the G-sensor gets the collision deceleration. The collision deceleration information
is converted in to digital data and compares them with designed data to decide whether it has to send a signal
to deploy the air bag module or not. If the calculation result by the CPU is correspond to the designed data, it
decides to send a deployment signal.
At the same moment, the safing sensor, which is linked linearly on deployment circuit, checks whether the
deceleration is happened by actual physical collision, or by other electronic waves and mal effect. So, only
when both the signal of deployment from the CPU and closing of safing sensor switch come together, the air
bag can be deployed.
Driver is protected by a steering wheel mounted air bag. Air bag-Supplemental Restraint System consists of Air
Bag Module, Air Bag Diagnostic Unit, and wire harness & clock-spring assembly.
Service warnings(Personal safety)
Failure to follow all warnings, cautions, notices and procedures could result in personal injury or death.
Power supply deactivation
Air bag-SRS diagnostic unit contains a backup power supply. Before disconnecting air bag-SRS components,
turn ignition switch to LOCK, disconnect battery (negative terminal first), and wait 10 minutes for backup power
supply to discharge.
Failure to follow this procedure could cause air bag modules to deploy during service procedures, which may
cause serious injury.
Safety equipment
• Always wear safety glasses when handling air bag modules.
• Always wear rubber gloves when handling deployed or damaged air bag modules.
Wiring and electrical components
Never service wiring or electrical components when any air bag is connected. When a procedure directs use of
a multimeter to probe pins of a connector, insert prbes into back of connector where possible.
If you must probes front face (terminal side), be certain to use a probe whose tip will not damage terminals
when it is inserted.
Component disassembly
Do not disassembly any air bag-SRS components.
Disassembly can render system inoperative, which may result in serious injury or death in event of an accident.
Never attempt to disassemble or repair air bag modules. Any attempt to adapt, re-use, or install an air bag
module or its components in another vehicle may result in serious injury or death to vehicle occupants in event
of an accident.
Air bag diagnostic unit (ADU)
Do not connect ADU connector unless ADU is securely installed. Shock of installation or pinching wiring
harness between module and its mounting points can cause air bags to deploy, which may cause serious
injury.
Air bag module inspection
Do not probe or inspect air bag modules or any of their connectors with an ohmmeter. Inspecting air bag
module with an ohmmeter, which supplies current, can cause air bags to deploy, resulting in serious injury.
Air bag module connector