Driver Airbag Module; To Replace Driver's Airbag - Lotus Evora Service Notes

Lotus Service Notes
WF.9 - DRIVER AIRBAG MODULE
WARNING: Safety precautions must be observed when handling a deployed airbag. After deployment,
the airbag surface may contain a white packing powder used to ease deployment. Always wear gloves
and safety glasses when handling a deployed inflator module, and wash your hands with a mild soap
and water afterwards.
The driver's airbag (or inflator module) is housed in the hub of the steering wheel, beneath a moulded trim
cover designed to hinge open in the event of deployment. The module comprises:
- an inflatable fabric bag;
- an inflator (canister of gas generating material)
- an initiator (or 'squib')
The complete module also serves as a horn operating pad, such that pressing anywhere on the steering
wheel centre trim will operate the horns. The module is spring mounted to a baseplate secured to the steering
wheel hub, the baseplate carrying 4 earthed electrical contacts which correspond with 4 opposing contacts
supplied with 12 volts and mounted on the module itself. Closing any of the contacts will ground the circuit
and sound the horns.
When the vehicle suffers a forward deceleration of sufficient magnitude to close both the safing sensor
and the integrated accelerometer within the SDM or one of the two forward crash sensors, current flows through
the stage 1 or stage 2 deployment loop of both the driver and passenger airbag module initiators and ignites
the gas generating material. Each bag inflates in a fraction of a second, the driver's bag bursting open the
steering wheel centre trim cover, and then deflates via vents in the bag, with the whole cycle taking less than
one second. The airbag is designed for a single deployment, and must then be renewed.
In order to help prevent unwanted deployment of the driver's airbag when servicing the steering column
or other SRS components, a shorting bar is incorporated into each of the two connector sockets on the rotary
connector (one connector for each airbag stage). The shorting bar operates when the connector is unplugged,
to short across the feed and return connections to the airbag. Thus, if a positive feed, or earth is inadvertently
applied to the connector terminals, both sides of the inflator module will be subject to the same electrical po-
tential, and no deployment will occur. The same feature is included in the airbag module connector sockets.

To replace driver's airbag

WARNING: The following procedures must be followed in the order listed to temporarily disable the
airbag system whilst working in the immediate vicinity of an airbag. Failure to follow this procedure
could cause unintended airbag deployment, resulting in personal injury and unnecessary airbag sys-
tem repairs.
1. Follow the safety procedure detailed in sub-section WF.6 to turn off the ignition, disconnect the battery
and unplug the rotary connector.
2. On the reverse side of the steering wheel, release the two Torx head screws, accessible via holes in the
plastic shroud around the steering wheel hub. Withdraw the airbag module and disconnect the two airbag
harness connectors and the two horn leads.
WARNING: When carrying a live airbag module, make sure the bag and trim cover are pointed away
from you. In case of an accidental deployment, the bag will then deploy with minimal chance of injury.
When placing a live airbag module on a bench or other surface, always face the bag and trim cover
upwards, away from the surface. This is necessary so that a free space is provided to allow the airbag
to expand in the unlikely event of accidental deployment.
3. If a driver's airbag is deployed, refer to steering sub-section HI.5 to determine whether the steering column
telescoping mechanism has been activated, and if necessary, renew the column assembly.
4. Mate the two harnesss connectors to the new airbag module sockets, matching the colour coding, and
connect the two horn leads. Locate the module into the steering wheel and retain with the two Torx head
retaining screws, tightening to 7 Nm.
Page 10
Section WF