:  Jan 7, 2008



COMPONENT LOCATION - SHEET 1 OF 2



1  - SRS (supplemental restraint system) warning indicator
2  - Driver air bag
3  - Clockspring
4  - Passenger air bag deactivation indicator
5  - Passenger air bag
6  - Passenger air bag deactivation switch (all except NAS (north American specification) and Australia)
7  - RCM (restraints control module)

COMPONENT LOCATION - SHEET 2 OF 2



1  - Door side impact sensor
2  - B pillar side impact sensor
3  - Rear quarter side impact sensor
4  - Third row side air curtain
5  - First and second row side air curtain
6  - Safety belt pretensioner and buckle switch
7  - Seat position sensor
8  - Occupant classification module (NAS only)
9  - Seat cushion pressure sensor (NAS only)
10  - Seat cushion pressure pad (NAS only)
11  - Safety belt tension sensor (NAS only)
12  - Side air bag
13  - Front impact sensors

GENERAL

The SRS (supplemental restraint system) provides additional protection for occupants in certain vehicle accident conditions. The SRS (supplemental restraint system) consists of:

The SRS features selective activation of the air bags and pretensioners, and two stage driver and passenger air bags. The RCM (restraints control module) monitors internal and external sensors and activates the required safety belt pretensioners and air bags if the sensors detect an impact or roll-over above preset limits.

DRIVER AIR BAG



1  - Release tool slot and guide channel
2  - Inflator stage 1 connector
3  - Inflator stage 2 connector
4  - Latch spring
5  - Locating pin and spring
6  - Latch hook

The driver air bag forms the center pad of the steering wheel. Four pins and two latches locate and secure the driver air bag to the steering wheel. The latches consist of wire springs on each side of the driver air bag which engage with hooks in the steering wheel. The driver air bag is released from the steering wheel by pulling on the wire springs with a special tool inserted through a slot on each side of the steering wheel hub. Springs on the locating pins then push the driver air bag away from the steering wheel.

A Lucar connector attaches a ground to the driver air bag.

The driver air bag has a two stage inflator, with separate electrical connectors for each stage. The inflator contains a non-azide propellant as the gas generator.

Lines moulded into the inner surface of the driver air bag cover provide weak points that split open in a controlled manner when the driver air bag deploys. The inflated volume of the air bag is 57 liters (2.01 ft3).

PASSENGER AIR BAG



1  - Reinforcement lid
2  - Chute
3  - Passenger air bag
4  - In-vehicle crossbeam
5  - Mounting bracket
6  - Lucar connector
7  - Inflator connector
8  - Deployment doors

The passenger air bag is located in the instrument panel, behind the upper glove compartment. The bottom of the passenger air bag is attached to a mounting bracket on the in-vehicle crossbeam. The top of the passenger air bag is attached to a chute, which, in turn, is attached to a reinforcement lid in the top of the instrument panel. When the air bag deploys, the chute guides the air bag to the underside of the reinforcement lid. The reinforcement lid incorporates two deployment doors that are forced open, splitting the instrument panel covering, when the air bag deploys.

A Lucar connector attaches a ground to the passenger air bag.

The passenger air bag has a two stage inflator, with separate electrical connectors for each stage. The inflator contains a non-azide propellant as the gas generator. The inflator uses a high pressure mix of air and hydrogen gas as the inflation medium. The inflated volume of the air bag is 130 liters (4.59 ft3).

SIDE AIR BAGS

:
  Left side air bag shown, right side air bag is mirror image



1  - Seat backrest frame
2  - Side air bag
3  - Cable
4  - Inflator

A side air bag is attached to the outside of each front seat backrest frame, under the backrest cover.

The side air bags are handed, and each consist of a moulded plastic case which contains the folded air bag and the inflator. A cable connects the igniter of the inflator to a connector in the main seat harness connector block located under the front edge of the seat cushion.

When the air bag deploys it forces the front edge of the moulded plastic case apart and splits open the backrest cover.

The side air bags use compressed argon as the inflation medium. The inflated volume of each side air bag is 12 liters (0.42 ft3).

SIDE AIR CURTAINS

The side air curtains are designed to protect the head and upper body in side impact and roll-over situations. The first and second row side air curtains are a standard fit on all vehicles. The third row side air curtains are fitted on seven seat vehicles only. The side air curtains use compressed argon as the inflation medium.

First and Second Row Side Air Curtain

:
  Right side air curtain shown, left side air curtain is mirror image



1  - Air curtain anchorage points
2  - Non inflatable section of air curtain
3  - Air curtain clip (manufacturing aid)
4  - Front gas guide attachment
5  - Inflatable section of air curtain
6  - B pillar ramp
7  - Securing screws
8  - Active tether device
9  - Rear tether anchor
10  - Rear tether
11  - Cant rail clip
12  - Gas guide pipe
13  - Inflator electrical connector
14  - Inflator
15  - Inflator mounting bracket

The first and second row side air curtains are installed on the cant rails above the front and rear doors, behind the headliner.

Each side air curtain has an inflator, which is attached to the header rail by a mounting bracket and two screws. The inflator is connected to the air curtain by a gas guide pipe.

The gas guide pipe and air curtain are secured along the cant rail by a fixing at the front of the gas guide pipe, two fixings at the B pillar ramp, two clips and two screws, and two fixings at the end of the gas guide pipe and C pillar ramp.

At the rear of the air curtain, an active tether device is clipped in two positions down the C pillar. At the bottom of the active tether device is a fixing anchorage.

The front of the air curtain is secured to the A pillar by two fixings.

When the side air curtain deploys, it breaks out of the B pillar ramp and the clips on the cant rail and extends downwards from behind the headliner. The deploying air curtain is tensioned between the anchorage points on the A pillar and the active tether device on the C pillar. This retains the air curtain in position against the upper part of the doors and the B pillar.

Third Row Side Air Curtain

:
  Right side air curtain shown, left side air curtain is mirror image



1  - Securing screw
2  - Air curtain
3  - Securing screw
4  - Rear tether
5  - Gas guide pipe
6  - Inflator mounting bracket
7  - Inflator
8  - Rear tether anchor
9  - Tether housing
10  - Rear tether
11  - Front tether anchor

The third row side air curtains are installed on the cant rails above the rear quarter windows, behind the headliner.

Each side air curtain has an inflator, which is attached to the D pillar by a mounting bracket and two screws. The inflator is connected to the air curtain by a gas guide pipe. The gas guide pipe and air curtain are secured to the cant rail by two screws. Tethers are attached to the front and rear of the air curtain. The front tether is anchored to the C pillar. The rear tether is anchored to the D pillar and held in position by a tether housing.

When a third row side air curtain deploys, it extends downwards from behind the headliner. The expanding air curtain tightens the tethers, which retain the air curtain in position against the rear quarter window.

PRETENSIONERS



1  - Safety belt buckle
2  - Boot
3  - Anchor bolt
4  - Piston and tube
5  - Electrical connectors for inflator and buckle switch

The pretensioners are used to tighten the front safety belts during a collision to ensure the occupants are securely held in their seats. A pretensioner is integrated into each front safety belt buckle.

Each pretensioner has a tube containing an inflator and a piston. The inflator is connected to the RCM (restraints control module) . The piston is attached to a steel cable, the opposite end of which is attached to the safety belt buckle.

On receipt of a fire signal from the RCM (restraints control module) , the inflator generates nitrogen gas that rapidly expands to drive the piston along the tube, pulling the cable and drawing the safety belt buckle downwards.

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 (restraints control module) . The RCM (restraints control module) broadcasts the status of the two front safety belts on the high speed CAN (controller area network) bus for use by the instrument cluster.

IMPACT SENSORS



Impact sensors are installed in the front and both sides of the vehicle. The use of multiple impact sensors provides shorter air bag trigger times, through faster detection of lateral and longitudinal acceleration, and improves detection accuracy.

There are two front impact sensors attached to brackets on the body front support frame, just above each front longitudinal.

There are six side impact sensors located in the passenger compartment, as follows:

Each impact sensor incorporates an accelerometer and a microcontroller powered by a feed from the RCM (restraints control module) . The power feed also provides the interface connection through which the impact sensor communicates with the RCM (restraints control module) using serial data messages. Acceleration is evaluated by the microcontroller and transmitted to the RCM (restraints control module) , which then makes the decision on whether or not to activate the air bags and pretensioners.

When the ignition is switched on the RCM (restraints control module) supplies power to the impact sensors, which perform a self test. After satisfactory self tests the impact sensors continually output 'sensor active' messages to the RCM (restraints control module) . If a fault is detected the relevant impact sensor sends a fault message, instead of the sensor active message, to the RCM (restraints control module) . The RCM (restraints control module) then stores a related fault code and illuminates the SRS (supplemental restraint system) warning indicator.

PASSENGER AIR BAG DEACTIVATION INDICATOR



1  - Deactivation indicator (NAS and Japan)
2  - Deactivation indicator (all except NAS and Japan)

The passenger air bag deactivation indicator is installed on the center switch pack of the instrument panel. When appropriate, the indicator illuminates to advise front seat occupants that the passenger air bag is disabled. Operation of the indicator is controlled by the RCM (restraints control module) based on seat occupancy status derived from the occupant classification system (NAS vehicles) or the passenger air bag deactivation switch (all except NAS and Australian specification vehicles).

The RCM (restraints control module) illuminates the indicator when:

PASSENGER AIR BAG DEACTIVATION SWITCH



The passenger air bag deactivation switch provides a method of manually disabling the passenger air bag on all vehicles except Australian specification and those fitted with the occupant classification system. The switch is installed in the front passenger end of the instrument panel and is operated by the ignition key.

When the passenger air bag deactivation switch is operated, it changes a ground connection between two pins in the connectors of the RCM (restraints control module) . When the passenger air bag deactivation switch is selected to OFF, the RCM (restraints control module) disables the passenger air bag and, if the front passenger seat is occupied, illuminates the passenger air bag deactivation indicator.

OCCUPANT SENSING

There are 2 types of occupant sensing:

Occupant Detection System



1  - Seat cushion
2  - Pressure switch

The occupant detection system can only determine if the front passenger seat is occupied or unoccupied. The occupant detection system consists of a pressure switch installed between the foam padding and the cover of the front passenger seat cushion.

The pressure switch incorporates a number of load cells connected in series and embedded in a plastic film. Weight on the pressure sensor increases the resistance of the circuit.

The instrument cluster supplies a reference voltage to the pressure switch and measures the current draw to determine the occupancy status. From the occupancy status, and the status of the front passenger safety belt (received from the RCM (restraints control module) on the high speed CAN (controller area network) bus), the instrument cluster determines the belt minder status.

Occupant Classification System

  : All Land Rover vehicles, with the exception of Defender, are equipped with passenger air bags. Passenger air bags offer well documented benefits in crash protection for adult front passenger seat occupants but their deployment can be harmful to children and infants sat in the front passenger seat of the vehicle. Land Rover recommends that children and infants are placed in the rear seats of the vehicle.

:
  All new Land Rover vehicles sold in North America comply with the FMVSS208 legislation due to the fitment of the occupant classifications system.



1  - Seat cushion
2  - Pressure pad
3  - Pressure tube
4  - Pressure sensor
5  - Safety belt tension sensor
6  - Occupant classification module

Occupant classification system comprises an ECU, attached to the underside of the seat, a silicon filled bladder with a pressure sensor fitted between the cushion foam and the seat pan and a seat belt tension sensor. When an occupant sits on the seat a pressure is created in the bladder and the occupant weight is determined from the pressure generated. The weight is compared against 4 classification thresholds. These are:

Classification Deactivation Indicator SRS Warning Indicator
Seat unoccupied OFF OFF
Occupied inhibit ON OFF
Occupied allow OFF OFF
Indeterminate state OFF ON

OCS module contains accelerometers and algorithms to compensate for the effects of longitudinal, lateral and vertical forces acting on the vehicle whilst being driven. The belt tension sensor is used to offset loads forced into the seat by 'cinched' child seats (where a child seat load on the seat is increased by a highly tensioned seat belt) and also dynamic belt loading (Off-road/aggressive driving styles).

The belt minder system on cars equipped with the occupant classification system uses the RCM (restraints control module) to detect seat occupancy status based on calculations within the RCM (restraints control module) , with the instrument cluster then determining whether a seat belt reminder should be activated based on the status of the seat belt buckle switches and vehicle speed.

SEAT POSITION SENSOR



1  - Seat frame
2  - Mounting plate
3  - Seat position sensor
4  - Electrical connector
5  - Target plate
6  - Seat base

The seat position sensor allows the RCM (restraints control module) to detect when the driver seat is forward of a given point on the seat track. The seat position sensor consists of a Hall effect sensor attached to the driver seat frame and a target plate on the seat base. While the ignition is on, the RCM (restraints control module) supplies the sensor with a power supply of 12V nominal, and monitors the return voltage. When the seat frame moves forwards, the sensor moves over the target plate, which changes the reluctance of the sensor. The change of voltage is detected by the RCM (restraints control module) and used as a switching point. The switching point is when the center of the sensor is 3 ± 4 mm from the leading edge of the target plate.

When the driver seat is forward of the switching point, the RCM (restraints control module) increases the time delay between firing the two stages of the inflator in the driver air bag. When the driver seat is rearward of the switching point, the RCM (restraints control module) uses the normal time delay between firing the two stages.

SRS WARNING INDICATOR



The SRS (supplemental restraint system) warning indicator consists of a red LED (light emitting diode) behind a SRS (supplemental restraint system) graphic in the tachometer of the instrument cluster.

Operation of the SRS (supplemental restraint system) warning indicator is controlled by a high speed CAN (controller area network) bus message from the RCM (restraints control module) to the instrument cluster. The RCM (restraints control module) illuminates the SRS (supplemental restraint system) warning indicator if a fault is detected, and for approximately 6 seconds during the bulb check at the beginning of each ignition cycle.

CLOCKSPRING



1  - Electrical connector for steering wheel switch packs and horn
2  - Inner rotor
3  - Outer housing securing lug
4  - Driver air bag link leads
5   Viewing window
6  - Drive peg
7  - Stopper
8  - Electrical connector for steering column harness
9  - Outer cover

The clockspring is installed on the steering column to provide the electrical interface between the fixed wiring harness of the steering column and the components that rotate with the steering wheel, i.e. the driver air bag, the horn and the steering wheel switch packs.

The clockspring consists of a plastic cassette which incorporates an outer cover fixed to the steering column and an inner rotor which turns with the steering wheel. Four securing lugs attach the cover to the multifunction switch on the steering column. The rotor is keyed to the steering wheel by a drive peg. A lug on the underside of the rotor operates the self-cancelling feature of the turn signal indicator switch. A ribbon lead, threaded on rollers in the rotor, links two connectors on the cover to two connectors on the rotor. Link leads for the driver air bag are installed in one of the connectors on the rotor.

To prevent damage to the ribbon lead, both the steering and the clockspring must be centralized when removing and installing the clockspring or the steering wheel. The clockspring is centralized when the drive peg is at six o'clock and 50 - 100% of a yellow wheel is visible in the viewing window.

Replacement clocksprings are fitted with a stopper, which locks the cover to the rotor, in the central position. The stopper must be broken off when the replacement clockspring is installed.

RCM (restraints control module)



The RCM (restraints control module) is installed on the top of the transmission tunnel, in line with the B pillars, and controls operation of the SRS. The main functions of the RCM (restraints control module) include:

A safing sensor in the RCM (restraints control module) provides confirmation of an impact to verify if air bag and pretensioner activation is necessary. A roll-over sensor monitors the lateral attitude of the vehicle. Various firing strategies are employed by the RCM (restraints control module) to ensure that during an accident only the appropriate air bags and pretensioners are fired. The firing strategy used also depends on the inputs from the safety belt switches and the occupant monitoring system.

An energy reserve in the RCM (restraints control module) ensures there is always a minimum of 150 milliseconds of stored energy available if the power supply from the ignition switch is disrupted during a crash. The stored energy is sufficient to produce firing signals for the driver air bag, the passenger air bag and the safety belt pretensioners.

When the ignition is switched on the RCM (restraints control module) performs a self test and then performs cyclical monitoring of the system. If a fault is detected the RCM (restraints control module) stores a related fault code and illuminates the SRS (supplemental restraint system) warning indicator. The faults can be retrieved by the Land Rover approved diagnostic system on a dedicated link between the RCM (restraints control module) and the diagnostic socket. If a fault that could cause a false fire signal is detected, the RCM (restraints control module) disables the respective firing circuit, and keeps it disabled during a crash event.

SRS OPERATION

General

In a collision, the sudden deceleration or acceleration is measured by the safing sensor in the RCM (restraints control module) and by the impact sensors. The RCM (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 air bags or pretensioners. During a collision, the RCM (restraints control module) only fires the air bags and pretensioners if the safing sensor confirms that the data from the remote sensor(s) indicates an impact limit has been exceeded. The RCM (restraints control module) also monitors the vehicle for a roll-over accident using the internal roll-over sensor and high speed CAN bus messages from the ABS (anti-lock brake system) module and the steering angle sensor.

The RCM (restraints control module) incorporates the following impact thresholds to cater for different accident scenarios:

The front impact thresholds increase in severity from pretensioners, through to driver and passenger air bag stage 2, belt fastened.

Firing Strategies

The seat belt pretensioners are fired when either the pretensioner impact limit or the roll-over limit is exceeded. The RCM (restraints control module) only fires the pretensioners if the related safety belt is fastened. For the front passenger pretensioner to fire, the seat must also be occupied by a large person, i.e. someone over a given weight (NAS only).

The driver and passenger air bags are only fired in a frontal impact that exceeds the stage 1 threshold. Both stages of the inflator in the driver and passenger air bags are fired. At impacts between the stage 1 and 2 thresholds, the delay between the firing of the two stages varies with the severity of the impact; the more severe the impact the shorter the delay. At stage 2 impact thresholds and above, the two stages of the inflator are fired almost simultaneously. The passenger air bag is disabled unless the front passenger seat is occupied by a large person (NAS only), or the passenger air bag deactivation switch is on (all except NAS). The time delay between firing the two stages of the inflator in the driver air bag is increased if the driver seat is forward of the seat position sensor switching point.

If there is a fault with a safety belt buckle sensor, the RCM (restraints control module) assumes the related safety belt is fastened for the pretensioner firing strategy and unfastened for the driver and passenger air bag firing strategies. If there is a fault with the occupant detection system, or if there is a fault with the passenger air bag deactivation switch, the RCM (restraints control module) increase the time delay between firing the two stages of the inflator in the passenger air bag.

If a side impact limit is exceeded, the RCM (restraints control module) fires the side air bag and the side air curtain(s) on that side of the vehicle. If the side impact limit on the front passenger side of the vehicle is exceeded, the RCM (restraints control module) also evaluates the input from the occupant classification system, and fires the side air bag only if the front passenger seat is occupied by a large person (NAS only).

The side air curtain(s) on both sides of the vehicle are fired if the roll-over limit is exceeded.

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

Crash Signal

When the RCM (restraints control module) outputs any of the fire signals, it also outputs a hard wired crash signal to the Engine Control Module (ECM) and changes the high speed CAN (controller area network) bus output message from 'no crash' to 'crash condition'. The high speed CAN (controller area network) bus message is used by the CJB (central junction box) and the FFBH (fuel fired booster heater).

On receipt of the crash signals:

The crash mode is cancelled by cycling the ignition switch.

CONTROL DIAGRAM - SHEET 1 OF 2 (ALL EXCEPT NAS)

:
  A = Hardwired connections; D = High speed CAN (controller area network) bus



1  - Fusible link 11E, BJB (battery junction box)
2  - Battery
3  - Left front impact sensor
4  - Right front impact sensor
5  - Left side impact sensor
6  - Right side impact sensor
7  - Passenger air bag deactivation switch
8  - Left safety belt buckle sensor
9  - Instrument cluster
10  - Right safety belt buckle sensor
11  - Occupant detection pressure sensor
12  - Seat position sensor
13  - RCM (restraints control module)
14  - Fuse 9P, CJB (central junction box)
15  - Ignition switch
16  - Fuse 68P, CJB (central junction box)
17  - Passenger air bag deactivation indicator

CONTROL DIAGRAM - SHEET 1 OF 2 (NAS ONLY)

:
  A = Hardwired connections; D = High speed CAN (controller area network) bus



1  - Fusible link 11E, BJB (battery junction box)
2  - Battery
3  - Left front impact sensor
4  - Right front impact sensor
5  - Left side impact sensor
6  - Right side impact sensor
7  - Left safety belt buckle switch
8  - Right safety belt buckle switch
9  - Instrument cluster
10  - Safety belt tension sensor
11  - Occupant classification module
12  - Pressure pad and sensor
13  - Seat position sensor
14  - RCM (restraints control module)
15  - Fuse 9P, CJB (central junction box)
16  - Ignition switch
17  - Fuse 68P, CJB (central junction box)
18  - Passenger air bag deactivation indicator

CONTROL DIAGRAM - SHEET 2 OF 2 (ALL MARKETS)

:
  A = Hardwired connections



1  - Passenger air bag
2  - Driver air bag
3  - Clockspring
4  - ECM (engine control module)
5  - Diagnostic socket
6  - Left pretensioner
7  - Left side air bag
8  - Left third row side air curtain
9  - Left first and second row side air curtain
10  - Right third row side air curtain
11  - Right first and second row side air curtain
12  - RCM (restraints control module)
13  - Right side air bag
14  - Right pretensioner