Lotus 2004 Eleven Service Notes page 474

Lotus Service Notes
WD.1 - GENERAL DESCRIPTION
The airbag Supplementary Restraint System (SRS) was introduced on the Lotus Elise for USA markets,
first produced for 2005 model year. This was then offered as an option for other LHD markets, and later for
RHD. From 2008 model year, all cars were so equipped. The SRS comprises driver and passenger frontal
airbags and pyrotechnic seat belt pre-tensioners for both the driver and passenger. The airbag system 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 10 inches {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 a vehicle mounted sensor, is sufficient to warrant airbag and seat
belt tensioning protection to both occupants. The airbag for the driver is housed in the centre of the steering
wheel, and that for the passenger in the front of the fascia. When triggered, 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. Initiated at the same time as the airbags is a pyrotechnic device on
each seat belt reel assembly, which uses a rack and pinion mechanism in order 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 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.
WD.2 - AIRBAG TELL TALE
A tell tale lamp in the instrument cluster will light for a few 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.
WARNING: If the airbag tell tale does not operate as described above, a fault in the SRS system is
indicated. The airbags may not inflate correctly or at all, or may inflate without warning. The system
should be interrogated using Lotus Scanner tools, and diagnosed and rectified without delay.
WD.3 - DATA LINK CONNECTOR (DLC)
In order to provide for communication
with the SRS Sensing and Diagnostic Module
(SDM), Lotus Scanner tools may be plugged
into the special 16 terminal harness connec-
tor socket, known as a Data Link Connector,
located off the main harness and accessible
from the passenger footwell. Communication
with engine management and anti-lock brakes
is also available via this connector.
Section WD
Main harness
Data Link Connector (DLC)
em235a
Page 3