Question:Is there any way I can accidentally set off
my air bag?
Answer:Yes. Most air bags are triggered electrically
by a signal from the vehicle's crash sensors and/or ABS control
module. It's about as failsafe a system as engineers can design.
The sensitivity threshold of the crash sensing system is set
high enough so that normal bumps and jolts cannot cause the bag
to go off. In fact, the air bag usually doesn't go off unless
the force of the impact is equivalent to hitting a sold barrier
at a speed of 15 to 18 mph or higher (which explains why the bag
may not go off in a minor fender bender). But there are some
circumstances where the bag may be inadvertently or accidentally
deployed.
One is an accidental electrical short. The wires that run
to the air bag are routed down the steering column and under the
dash along with dozens of other wires. If you're doing electrical
work under the dash and short out a hot wire to one of the wires
in the air bag circuit, it could result in a rather loud and unexpected
boom from the air bag. The bag deploys with explosive force,
which might injure you if you're in the way. The counterforce
generated by the bag is designed to protect occupants who are
wearing seat belts and facing forward in an upright position,
not someone who is working on the car or just sitting behind the
wheel.
To prevent this from happening, always disconnect one of the
battery cables before doing any electrical work or working on
any part of the air bag system (including the steering wheel).
Emergency rescue personnel such as paramedics and police officers
are trained how to deactivate air bags. This may be necessary
if a person is trapped in a vehicle with an air bag and the air
bag has not deployed. The last thing they want is the air bag
exploding as they're trying to extract an injured person from
the wreckage. Disconnecting the battery doesn't necessarily deactivate
the air bag because the control module often contains an internal
battery that keeps the system armed for up to several minutes.
This is actually a safety feature that allows the air bag to
work in case the battery cables are severed during a crash.
Many air bag equipped vehicles have a special orange or yellow
connector at the base of the steering column that can be disconnected
to temporarily disable the air bag. The ignition must be off
when this connector is disconnected or reconnected. The connector
may have a tag labeled SRS (Supplemental Restraint System) connector
or SIR (Supplemental Inflation Restraint) connector.
Another situation where an accidental air bag deployment may
occur is when plowing snow with a truck or sport utility vehicle
fitted with a snow blade. Due to the severe jolts or bumps that
may occur when ramming into things with a blade, the air bag system
should be deactivated prior to plowing by removing the system
fuse or unplugging the air bag connector(s) per the vehicle manufacturer's
instructions.
The same situation may occur when off-roading in a four-wheel
drive vehicle. Again, deactivating the air bag will prevent jolts
and bumps from setting it off.
A final word about air bags: they are designed to deploy and
protect in frontal collisions only (except for Volvo's new side
impact system which also protects during side collisions). The
air bag is not supposed to go off in a side collision, if the
vehicle is rear ended or rolls over (but they sometimes do).
