2010 JAGUAR XFR seat control module

Published: 30-May-2012
Supplemental Restraint System - Air Bag and Safety Belt Pretensioner
Supplemental Restraint System (SRS) - Overview
Description and Operation

OVERVIEW


WARNING: All pyrotechnic devices are dangerous. Before performing any procedures on any pyrotechnic device, read all
information contained within the Standard Workshop Practices section of this manual.
Refer to: Standard Workshop Practices (100-00 General Information, Description and Operation).
The SRS (supplemental restraint system) provides additional protection for the vehicle occupants in certain impact conditions.
The system is controlled by the RCM (restraints control module), which is mounted beneath the floor console. The system
includes twin stage drivers and front passenger airbags.
The RCM receives inputs from various sensors around the vehicle and determines which, if any, airbags should be deployed.
The SRS features an occupant detection system. The occupant detection system comprises a mat fitted inside the front passenger seat. By monitoring the condition of the mat, the RCM can determine if the front passenger seat is occupied. It uses this information to determine which airbags to deploy in the event of an impact. This information is also used to illuminate the
safety belt instrument cluster warning lamp if the front passenger seat is occupied and the safety belt is not engaged.

North American Specification (NAS) vehicles also feature an occupant classification system. The occupant classification system
comprises a control module, pressure pad and safety belt tension sensor. The system can determine the size and weight of the
front seat passenger. This information is transmitted to the RCM over the high speed CAN (controller area network) bus. The RCM uses this information to help determine which airbags to deploy in the event of an impact.

6 Occupant classification system pressure pad (NAS only) 7 Passenger airbag deactivation LED (light emitting diode) 8 Instrument cluster 9 Occupant detection system pad (all, except NAS) 10 Driver's seat position sensor 11 Front passenger seat safety belt pretensioner 12 Driver's seat safety belt pretensioner 13 LH (left-hand) front impact sensor 14 RH (right-hand) front impact sensor 15 RH rear impact sensor 16 RH side impact sensor 17 LH rear impact sensor 18 LH side impact sensor 19 RCM (restraints control module)

Item Description 1 Battery 2 BJB 3 RJB 4 Front passenger airbag 5 Clockspring 6 Driver's airbag 7 Front passenger seat safety belt switch 8 Driver's seat safety belt switch 9 LH curtain airbag 10 Driver's seat thorax airbag 11 Front passenger seat thorax airbag 12 RH curtain airbag 13 RCM


System Operation System Operation

In a collision, the sudden deceleration or acceleration is measured by the impact sensors and the accelerometers in the
restraints control module. The restraints control module evaluates the readings to determine the impact point on the vehicle
and whether the deceleration/acceleration readings exceed the limits for firing any of the airbags, pretensioners, and battery
disconnect unit. During a collision, the restraints control module only fires the airbags and pretensioners if the safing function
confirms that the data from the impact sensor(s) indicates an impact limit has been exceeded.
The RCM incorporates the following impact thresholds to cater for different accident scenarios: Front impact, pretensioners
Front impact, driver and passenger airbags stage 1, belt unfastened
Front impact, driver and passenger airbags stage 1, belt fastened
Front impact, driver and passenger airbags stage 2, belt unfastened
Front impact, driver and passenger airbags stage 2, belt fastened
Rear impact
Driver side impact
Passenger side impact.

The front impact thresholds increase in severity from pretensioners to driver and passenger airbag stage 2, belt fastened (refer
to list above).

Firing Strategies

The safety belt pretensioners are fired when the pretensioner impact limit is exceeded. The RCM only fires the pretensioners if the related safety belt is fastened.

The driver and passenger airbags are only fired in a frontal impact. If an impact exceeds a stage 1 limit, but is less than the
corresponding stage 2 limit, only one inflator in each airbag is fired (stage 2 is still fired for disposal after a delay of 100ms).
If an impact exceeds the stage 2 limit, the two inflators in each airbag are fired simultaneously.

The passenger airbag is disabled unless the front passenger seat is occupied by a large person (NAS only), or the passenger
airbag deactivation switch is on (all except NAS & AUS).

The stage 2 inflator of the driver airbag is disabled if the driver seat is forward of the switching point of the seat position
sensor.

If there is a fault with a safety belt buckle sensor, the RCM assumes the related safety belt is fastened for the pretensioner firing strategy and unfastened for the driver and passenger airbag firing strategies. If there is a fault with the occupant
classification sensor, the RCM disables the passenger airbag. If there is a fault with the passenger airbag deactivation switch, the RCM disables the passenger airbag.
If a side impact limit is exceeded, the RCM fires the side airbag and the side head airbag on that side of the vehicle. If the side impact limit on the front passenger side of the vehicle is exceeded, the RCM also evaluates the input from the occupant classification sensor, and fires the side airbag only if the front passenger seat is occupied by a large person (NAS only).

If multiple impacts occur during a crash event, after responding to the primary impact the RCM will output the appropriate fire signals in response to any further impacts if unfired units are available.

Front and Rear Impact Firing Strategy (All Except NAS)
Safety Belt Status Strategy Driver Passenger Applicable Pretensioner Driver airbag Passenger airbag Fastened - Fired at pretensioner threshold Fired at belt fastened threshold - Unfastened - Not fired Fired at belt unfastened threshold - - Fastened Fired at pretensioner threshold - Fired at belt fastened threshold - Unfastened Not fired - Fired at belt unfastened threshold www.JagDocs.com

Operation of the airbag warning indicator is controlled by a high speed CAN bus message from the RCM to the instrument cluster. The RCM sends the signal to illuminate the airbag warning indicator if a fault is detected, and for approximately 6 seconds during the bulb check at the beginning of each ignition cycle.

Occupant Monitoring

There are two types of occupant monitoring:

In all markets except NAS & Australia, vehicles have an occupant detection sensor
In NAS markets, vehicles have an occupant classification system

For markets which have an occupant detection sensor, this has no interface with the restraints system and only provides the
belt reminder function.

For markets that have an occupant classification system, this provides the RCM with the occupancy status of the front passenger seat. The restraints control module uses this and the seat buckle status in the evaluation of the firing strategy for
the passenger front airbag, side airbag, and pretensioner.

Safety Belt Sensors

The buckle of each front safety belt incorporates a Hall effect sensor that provides a safety belt status signal to the RCM. The RCM broadcasts the status of the two front safety belts on the high speed CAN bus for use by the instrument cluster. In the event of a front impact the RCM will deploy the pretensioners provided the safety belt buckles are fastened. The safety belt buckle pretensioners have a lower deployment threshold than that required by the airbags. Hence it is possible during a minor
collision, which exceeds the deployment threshold and will deploy only the safety belt buckle pretensioners. Airbag Warning Indicator

Published: 11-May-2011
Supplemental Restraint System - Occupant Classification Sensor
Removal and Installation

Removal

WARNINGS:


To avoid accidental deployment, the restraints control module backup power supply must be depleted. Wait at least one
minute after disconnecting the battery ground cable(s) before commencing any repair or adjustment to the supplemental
restraint system (SRS), or any component(s) adjacent to the SRS sensors. Failure to follow these instructions may result in
personal injury.


Always wear safety glasses when working on an air bag equipped vehicle and when handling an air bag module. Failure to
follow this instruction may result in personal injury.


To minimize the possibility of premature deployment, do not use radio key code savers when working on the
supplemental restraint system. Failure to follow this instruction may result in personal injury.


To minimize the possibility of injury in the event of premature deployment, always carry a live air bag module with the
bag and trim cover pointed away from the body. Failure to follow this instruction may result in personal injury.


To minimize the possibility of premature deployment, live air bag modules must only be placed on work benches which
have been ground bonded and with the trim cover facing up. Failure to follow these instructions may result in personal injury.


Never probe the electrical connectors of air bag modules or any other supplemental restraint system component. Failure
to follow this instruction may result in personal injury.


Painting over the driver air bag module trim cover or instrument panel could lead to deterioration of the trim cover and air
bags. Do not for any reason attempt to paint discoloured or damaged air bag module trim covers or instrument panel. Install a
new component. Failure to follow this instruction may result in personal injury.
CAUTIONS:


The front passenger seat occupant classification sensor is available only as a service kit. No attempt should be made to
replace individual components. Failure to follow this instruction may result in personal injury.


Check for correct operation of the front seat after completion of the procedure to make sure that the wiring harness has
not become trapped or stretched.
NOTES:


Note the routing of the seat harness.


Some variation in the illustrations may occur, but the essential information is always correct.

1. Make the air bag supplemental restraint system (SRS) safe.

Refer to: Standard Workshop Practices (100-00 General Information, Description and Operation).

2. Refer to: Battery Disconnect and Connect (414-01 Battery, Mounting and Cables, General Procedures).

3. Refer to: Front Seat Backrest Cover (501-10 Seating, Removal and Installation).

- Disadvantage: Scarring and hardening of the surface.
Flattening using a copper electrode.
- Small, sharp dents that face outwards can be worked on with a copper electrode.
Flattening using a flame and body files.

NOTE: When applied correctly, this method can be used with all the attached parts still in place (roof headlining,
wiring harnesses etc.).

- Small, soft dents (only slight stretching): Working at the edges of the dent in an inward spiral pattern, the dent
is heated with an oxyacetylene torch (torch size 1 - 2 mm, excess gas flame) to approx. 250° C.
- Working rapidly with a body file extracts heat from the edge area until the dent is flattened. Preferably alternate
between two files. This increases the amount of heat that can be extracted.

Safety measures

The electronic control modules (ECM) fitted to vehicles make it advisable to follow suitable precautions prior to carrying
out welding repair operations. Harsh conditions of heat and vibration may be generated during these operations which
could cause damage to the modules. In particular, it is essential to follow the appropriate precautions when
disconnecting or removing the airbag RCM.
Do not allow electronic modules or lines to come into contact with the ground connection or the welding electrode.
Seat belt anchorages are a safety critical. When making repairs in these areas, it is essential to follow design
specifications. Note that extra strength low alloy steel may be used for seat belt anchorages. Where possible, the
original production assembly should be used, complete with its seat belt anchorages, or the cut line should be so
arranged that the original seat belt anchorage is not disturbed.
All welds within 250mm (9.842) of seat belt anchorages must be carefully checked for weld quality, including spacing of
spot welds.
Remove the battery before carrying out welding work in its vicinity.
Utmost care must be taken when welding near the fuel tank or other components that contain fuel. If the tank filler
neck or a fuel line must be detached to allow access for welding work, then the fuel tank must be drained and removed.
Never weld, on components of a filled air conditioning system. The same applies if there is a risk of the air conditioning
system heating up.
Connect the ground connection of the electrical welder directly to the part that is to be welded. Make sure that there
are no electrically insulating parts between the ground connection and the welding point.
Adjacent vehicle parts and adjacent vehicles must be shielded against flying sparks and heat.

Pedestrian protection system

The pedestrian protection system is designed to mitigate injuries in a pedestrian collision with the vehicle. It does this by
utilizing a pair of pyrotechnic actuators to lift the hood away from the engine, creating a cushioned impact between the
pedestrian and the vehicle. It is essential that any repair or replacement operations do not affect the safe working of the
system.
For additional information, refer to: Pedestrian Protection System (501-20C Pedestrian Protection System, Description and Operation).

Resistance spot welding

Where resistance spot welds have been used in production, they must be reproduced with new spot welds in replacement
where possible. All such reproduction spot welds should be spaced 25 to 30mm apart.
Setting up the equipment and co-ordinating the welding parameters.

Equipment:
- Follow the equipment manufacturer's instructions for the equipment settings.
- Select the correct electrode arms (as short as possible).
- Align the electrode arms and tips exactly.
- Electrode tips should be convex (rough shaping with a file, fine shaping with a sanding block).
Body:
- Make sure that the flanges to be joined lie perfectly flat to one another.
- Prepare a bare metal joint surface (inside and outside).
Notes on technique/method:
- Carry out a test weld on a sample piece of the material coated in welding paste.
- If any metal parts are located between the electrode arms then there will be a loss of induction and therefore
power (adjust current setting).
- The power needs to be adjusted for high-strength low alloy steel.
- Repeated welding on old welding points often leads to poor quality welds.
- Keep the electrode tips as near as possible to an angle of 90° to the contact surface.
- Keep the pressure on the electrodes for a short period after finishing the weld.
- The electrodes work best if their shape is convex. Clean the contact surface of the electrodes regularly.
Resistance spot welding panels where the total thickness is 3 mm or more

For all repairs to modern Jaguar vehicles, spot-welding equipment should be suitable for reliable welding of zinc-plated,
high-strength and high-tensile steels in three or more layers, up to 5 mm total thickness. If these requirements are not
fulfilled, plug welding must be used for safety reasons. The electrical specifications (current, resistance, heat) of the
spot-welding equipment have different validity, depending upon the type of equipment. Therefore, it is essential that the
manufacturer's instructions are observed with regard to the actual welding performance.
www.JagDocs.com

Panel Sheet Metal Repairs, Removal and Installation).

7. Remove the side air curtain module.
For additional information, refer to: Side Air Curtain Module (501-20B Supplemental Restraint System, Removal and Installation).

8. Remove the front seat.
For additional information, refer to: Front Seat (501-10 Seating, Removal and Installation).

9. Remove the floor covering.

10. If the passenger side A-pillar reinforcement is to be repaired, remove
the heater core and evaporator core housing.
For additional information, refer to: Heater Core and Evaporator Core Housing (412-01 Climate Control, Removal and Installation).
11. If the right-hand A-pillar reinforcement is to be repaired, remove the
central junction box.
For additional information, refer to: Central Junction Box (CJB) (418-00 Module Communications Network, Removal and Installation).

12. If the drivers side A-pillar reinforcement is to be repaired, remove the
pedal box.

13. Release and lay aside the insulating material at the inner bulkhead.

14. Release and position aside the inner bulkhead and floor panel wiring
harness.


15. NOTE: The NVH components may have already been
removed on the outer panel.

Remove the upper and lower NVH components and if
undamaged retain for reuse.