the seat belt by assuring that the belt is tight about
the occupant early in a collision. Tensioners are
designed to work for all size occupants.
These devices are not a substitute for proper seat
belt placement by the occupant. The seat belt still
must be worn snugly and positioned properly.
The tensioners are triggered by the Occupant
Restraint Controller (ORC). Like the front airbags,
the tensioners are single use items. After a collision
that is severe enough to deploy the airbags and ten-
sioners, both must be replaced.
PASSIVE RESTRAINTS - AIRBAG SYSTEM
The Passive Restraints are referred to as a supple-
mental restraint system because they were designed
and are intended to enhance the protection for the
occupants of the vehicle ONLY when used in con-
junction with the seat belts or active restraints. They
are referred to as passive restraints because the
vehicle occupants are not required to do anything to
make them operate; however, the vehicle occupants
must be wearing their seat belts in order to obtain
the maximum safety benefit from the supplemental
restraint system.
The supplemental restraint system electrical cir-
cuits are continuously monitored and controlled by a
microprocessor and software contained within the
Occupant Restraint Controller (ORC). An airbag indi-
cator in the Instrument Cluster illuminates for about
seven seconds as a bulb test each time the ignition
switch is turned to the ON or START positions. Fol-
lowing the bulb test, the airbag indicator is turned
ON or OFF by the ORC to indicate the status of the
supplemental restraint system. If the airbag indica-
tor comes on at any time other than during the bulb
test, it indicates that there is a problem in the sup-
plemental restraint system electrical circuits. Such a
problem may cause airbags not to deploy when
required, or to deploy when not required.
Deployment
of
the
supplemental
restraints
depends upon the angle and severity of an impact.
Deployment is not based upon vehicle speed; rather,
deployment is based upon the rate of deceleration as
measured by the forces of gravity (G force) upon the
impact sensors. When an impact is severe enough,
the microprocessor in the ORC signals the inflator of
the appropriate airbag units to deploy their airbag
cushions. The front seat belt tensioners are provided
with a deployment signal by the ORC in conjunction
with the front airbags and driver knee blocker air-
bag. During a frontal vehicle impact, the knee block-
ers work in concert with properly fastened and
adjusted seat belts to restrain both the driver and
the front seat passenger in the proper position for an
airbag deployment. The knee blockers also absorb
and distribute the crash energy from the driver and
the front seat passenger to the structure of the
instrument panel. The seat belt tensioner removes
the slack from the front seat belts to provide further
assurance that the driver and front seat passenger
are properly positioned and restrained for an airbag
deployment.
When the ORC monitors a problem in any of the
airbag system circuits or components, including the
seat belt tensioners, it stores a fault code or Diagnos-
tic Trouble Code (DTC) in its memory circuit and
sends an electronic message to the cluster to turn on
the airbag indicator. Proper testing of the airbag sys-
tem components, the Programmable Communications
Interface (PCI) data bus, the electronic message
inputs to and outputs from the cluster or the ORC,
as well as the retrieval or erasure of a DTC from the
ORC or cluster requires the use of a DRBIII
t scan
tool. Refer to the appropriate Body Diagnostic Proce-
dures manual.
The ORC determines if an impact is severe enough
to require the airbags to inflate. Based on the level of
collision severity, the ORC determines the proper
rate of inflation. The front airbag inflators are
designed to provide different rates of airbag inflation.
The ORC will not detect roll over collisions.
The ORC also monitors the readiness of the elec-
tronic parts of the system whenever the ignition
switch is in the START or ON positions. If the key is
in the OFF position, in the ACC position, or not in
the ignition switch, the front airbags are not on and
will not inflate.
The ORC sends a message to the cluster to turn on
the AIRBAG light in the instrument panel for 6 to 8
seconds when the ignition switch is first turned ON,
then turns the light OFF. If the ORC detects a mal-
function in any part of the system, the airbag light
will turn ON either momentarily or continuously.
When the ORC detects a collision requiring the
Front Airbags, it signals the inflator units. A large
quantity of nontoxic gas is generated to inflate the
front airbags. Different front airbag inflation rates
are possible, these rates are determined by the ORC
based on collision severity. The front airbag covers
separate and fold out of the way as the front airbags
inflate to their full size. The front airbags fully
inflate in about 50 milliseconds. This is only about
half of the time it takes you to blink your eyes. The
front airbags then quickly deflate while helping to
restrain the driver and front passenger. The driver’s
and passenger’s front airbag gas is vented through
the airbag material and small vent openings towards
the instrument panel. In this way the front airbags
do not interfere with your control of the vehicle.
The
Supplemental
Curtain
Airbags
are
designed to activate only in certain side collisions.
When the ORC detects a collision requiring the cur-
CS
RESTRAINTS
8O - 5
RESTRAINTS (Continued)