Lotus 2004 ELISE Service Notes page 423

Lotus Service Notes
Inspections Required After an Accident
All SRS system components, including harnesses and brackets, must be inspected after an accident. If
any are damaged or bent, they must be replaced even if a deployment did not occur.
the following components MUST be renewed even if there is no visible damage to the parts:
Driver airbag module;
Passenger airbag module;
Sensor & Diagnostic Module (SDM);
Driver and passenger pyrotechnic seat belt assemblies;
Rotary connector;
Passenger airbag mounting brackets (2);
Passenger airbag shute (2);
Passenger airbag door assembly (trim panel);
Dash panel upper extrusion.
Inspect the steering column for damage or telescoping (see Section HG) and column mounting brackets
for damage. Inspect the chassis scuttle beam in the area of the passenger airbag mounting brackets for
damage or distortion. Inspect the SRS wiring harness and connectors for damage or any signs of overheating.
Do not attempt to repair the steering column or chassis or any of the above mentioned components. Service
is by replacement only.
WARNING: Proper operation of the SRS system requires that any repairs to the vehicle structure
return it to its original production configuration. Deployment, or any visible damage to the SRS com-
ponents and/or their respective mounting brackets requires replacement, not repair.
WD.7 - THEORY OF OPERATION
The key components of the Supplementary Restraint System (SRS) are the following:
• Sensor & Diagnostic Module (SDM);
• Driver airbag module;
• Passenger airbag module;
• Rotary connector;
• Seat belt pre-tensioners.
Sensor & Diagnostic Module (SDM)
The SDM is the main electronic control unit (ECU) of the SRS, whose function is to detect rates of forward
deceleration, and when interpreted as a collision accident requiring supplementary occupant protection, the
SDM triggers as a single set, the driver and passenger airbags and both seat belt pre-tensioners. Additional
functions are to maintain an energy reserve in case of vehicle battery power interruption, operation of a dash
mounted tell tale lamp, and a electronic diagnostic and event recording facility accessible via a workshop
scanner tool.
The unit is mounted by a dedicated bracket to the top of the passenger side scuttle beam, accessible after
removal of the fascia top.
The following functionality is provided by the SDM;
•
Sensing of frontal impact crash events and vehicle specific discrimination between non-deployment and
deployment-requiring events as well as the deployment of the frontal airbags and seat belt pre-tensioners.
•
In case of a required deployment, timely activation of the activation current for the deployment loops.
•
Detection of electrical system faults which may influence the readiness of the system to deploy, or in-
crease the probability of an inadvertent deployment by:
- continuous electrical monitoring of all deployment circuits (without any effect on the readiness of the
system);
- continuous monitoring of the supply voltage and the lamp circuitry (dependent on lamp driver activation
status);
- SDM self test;
- activation of a tell tale lamp in case of a detected system fault.
Page 8
Section WD
If the SRS was deployed,