Lotus Evora Service Notes page 358

Lotus Service Notes
WF.1 - GENERAL DESCRIPTION
The Lotus Evora is equipped with dual stage airbags for both the driver and front seat passenger, in con-
junction with pyrotechnic seat belt pre-tensioners for both front seat occupants. The airbag Supplementary
Restraint System (SRS) is supplemental to the seat belts, and does not render the seat belts redundant. Seat
belts have proven to be the single most effective safety device, and should be worn at all times by both driver
and passenger, no matter how short the journey. Properly worn seat belts also ensure that the seat occupant
is in the best position for full effectiveness of the airbag.
WARNING: Airbags inflate with great force, in a fraction of a second, and if a vehicle occupant is too close
to the airbag (less than 250 mm) or incorrectly positioned, they could be killed or seriously injured.
The SRS is designed to operate when the vehicle is involved in a frontal, or near frontal collision, and the
impact (rate of deceleration) as detected by any one of three vehicle mounted sensors, is sufficient to warrant
airbag and seat belt tensioning protection to both front seat occupants. The 55 litre airbag for the driver is housed
in the centre of the steering wheel, with a 100 litre bag for the passenger housed within the fascia. Three 'G'
sensors are mounted in the vehicle to detect the rate of deceleration in a collision, and if the signal from any
one of these should exceed a threshold value, the first stage of airbag inflation will be initiated. This will cause
the airbags to inflate at a rate calculated to provide appropriate protection, whilst minimising the potential for
airbag induced injury, especially where an occupant is not positioned optimally at the triggering moment. If a
higher rate of deceleration is detected, indicating a more severe impact, the second stage inflator modules will
be triggered to more rapidly inflate the airbags. In either case, both bags inflate in a fraction of a second to
form a cushion for the driver's and passenger's upper bodies. The bags then deflate very rapidly to minimise
any obstruction to the driver. Note that in order to protect against the danger of an unprogrammed firing of the
second stage after a first stage airbag deployment, with the potential to cause injury to the vehicle occupant or
carer, any first stage firing is followed almost immediately by triggering of the second stage, too late to affect
the speed of airbag inflation, but ensuring that the airbag is then 'dead' and in a stable condition.
Initiated at the same time as the airbags is a pyrotechnic device on each front seat belt reel assembly,
which uses rapid gas generation and a train of balls in a track to apply a tightening force to the belt reel and
remove any slack from the belt. The force sustained by the belt and its user during the event, is then controlled
by a torsion bar within the belt reel to limit the deceleration force to which the occupant is subjected.
Note that the SRS will deploy only in moderate to severe frontal and near frontal collisions, and is not
designed to be triggered in rollover, rear or low speed frontal collisions, or in some types of side impacts.
The system incorporates a self-diagnostic facility, which continuously monitors the SRS electrical circuits
for faults, and if necessary, lights a tell tale lamp in the instrument cluster. Most components of the SRS will
require replacement after an airbag deployment.
Passenger Airbag Defeat (PAB) Switch
If a rearward facing child seat is to be used in the front passenger seat of the Evora, it is essential to switch
off the passenger airbag. If an accident should occur and trigger airbag inflation, the back of the seat could be
subjected to a force sufficient to seriously injure or kill the child.
A PAB switch is located at the end of the passenger fascia, and is operated using the mechanical ignition
key; insert the key and turn clockwise to the 'OFF' position, and withdraw the key. With the ignition switched
on, a tell tale lamp in the instrument panel will light up red as a reminder that the passenger airbag has been
disabled. To reinstate airbag operation, insert the key in the PAB switch and turn counterclockwise.
WF.2 - AIRBAG TELL TALE
The airbag safety system, including the pre-tensioning seat belts, has a self-diagnostic feature which
lights the red tell tale and sounds an audible alert if a fault is detected. As a circuit check, the tell tale will light
for about six seconds following ignition switch on, and then go out. If the lamp remains lit, or comes on at any
other time, a fault in the airbag system is indicated, which should be rectified without delay.
WARNING: If the airbag tell tale is lit, the airbags may not inflate correctly in a crash, or may inflate
without warning; or the pre-tensioning seat belts may not perform correctly. The SRS should be inter-
rogated using the Lotus TechCentre and diagnosed and rectified without delay.
Section WF
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