05-09-40-002G

Service Bulletin
File in Section:
09 - Restraints
Bulletin No.:
05-09-40-002G
Date:
June, 2013
INFORMATION
Subject:
Safety Belt Locking Conditions (Normal Operating Characteristic)
Models:
2005-2014 GM Passenger Cars and Light Duty Trucks
This bulletin has been revised to add the 2013-2014 model years. Please discard Corporate
Bulletin Number 05-09-40-002F.
The purpose of this bulletin is to explain when the
safety belts are supposed to lock. There are several
different locking situations for both front and rear safety
belts.
Overspool Lock
There is an unintentional locking condition that ALL
safety belts from ALL manufacturers may experience
called “overspool lock.” If the webbing snaps back to
the stowed position rapidly enough, the retractor will
lock with the belt fully stowed. This is more likely to
occur when customers “help” the belt to retract. Without
the weight of the latch plate and friction to slow the
retractive speed of the webbing, the higher than normal
webbing retraction speed that occurs engages the
locking mechanism when a sudden stop occurs at the
end of web travel. Since the webbing is now fully
loaded on the spool, the retractor cannot rewind itself
further to release the locking mechanism. When this
happens, the occupant cannot extract the belt to wear
it. DO NOT replace the retractor for this condition
until first attempting to disengage the locking
mechanism by following the recommendation listed
below.
Recommendation
Pull hard on the locked webbing and then release. The
hard pull extracts a small amount of webbing from the
retractor which, in turn, permits a small amount of
retraction to occur when released. This is all that is
needed to disengage the locking mechanism. The
safety belt will now function properly.
Copyright 2013 General Motors LLC. All Rights Reserved.
Vehicle Sensing
This type of locking occurs in response to the vehicle
under the following conditions:
– The vehicle changes speed or direction abruptly (the
vehicle goes into rapid acceleration OR rapid
deceleration or there is aggressive cornering).
– It can also occur in a static condition when a vehicle
is parked on a large slant (fore-aft or side-to-side),
such as streets in San Francisco, California.
– It may also occur over rough road conditions where
the retractor mechanism is bounced into a locked
condition.
In all of these conditions, as long as tension is
maintained on the webbing, the belt will stay locked.
When the tension is released, the belt retracts slightly,
the lock bar disengages and the safety belt should
return to normal function. Please inform customers that
may comment that “the belt locks intermittently” that
this is the design intent and the belt is functioning
properly.
Web Sensing
This type of locking occurs in response to the extraction
of webbing. When the webbing reels out at an
accelerated rate, it goes into lock mode and stays there
until tension is again released. To observe this
condition, extract the webbing quickly. Customers may
refer to this condition as “intermittent lock-up” and
encounter it when trying to put the belt on too quickly.
Page 2
June, 2013
Automatic Locking (ALR)
When the webbing is pulled all the way out, it
automatically converts the retractor into a cinch-down
mode (i.e. ALR). This is typically used to tightly secure
a child seat to the vehicle. Some customers may
experience inadvertent activation of ALR mode if they
happen to pull the belt all the way out to the end of
travel while they are putting the belt on. The ALR mode
of operation is automatically cancelled when the belt is
unfastened and stowed (the belt returns to normal
sensitive function).
Bulletin No.: 05-09-40-002G
The ALR locking mode is also provided at the driver's
position of the Corvette only, as a unique feature.
Corvette customers may find this feature appealing
when they plan to operate the vehicle in a “spirited”
manner (such as driving in mountainous terrain). With
the ALR active, the operator is snugly cinched into the
seat and kept firmly in place during high G-force driving
maneuvers.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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