Land Rover Defender: Description

RCM

NOTES:

• RHD vehicle is shown, LHD vehicle is similar.
• Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The RCM is located under the floor console and controls the operation of the SRS. The RCM receives an ignition feed from the Body Control Module (BCM)/ Gateway Control Module (GWM).

The RCM includes the following functions:

• Impact detection and recording.
• Airbag and seatbelt pretensioner firing.
• Self-test and system monitoring, with status indication through the airbag warning indicator and non volatile storage of fault information.
• Supply of yaw rate and lateral acceleration data for the Anti-Lock Brake System Control Module (ABS) and other modules requiring vehicle motion information.

The RCM determines which elements of the SRS are to be deployed by using 2 internal areas:

• Impact severity evaluation
• Deployment handler.

Impact severity evaluation uses data from the RCM internal accelerometer, the front impact sensors and the seatbelt buckle switches. Based on this data, the RCM decides which level of airbag module deployment is required and sends the information to the second area, the deployment handler.

The deployment handler evaluates the status of the seat track position sensor, seatbelt buckle switches and, on NAS market vehicles, the occupant classification sensor system.

The RCM has the ability to detect roll-over condition and apply the relevant airbag deployment strategy. The RCM processes the acceleration data and, subject to an impact being of high enough severity, decides which airbags should be deployed.

Pitch/roll/yaw rate and longitudinal/lateral/vertical accelerations for the ABS and all other modules requiring vehicle motion data are derived from the internal accelerometer. The data is transmitted on the FlexRay.

On board testing of the airbag and pretensioner firing circuits, the warning indicator circuits and the RCM status is done by the RCM. The RCM can store Diagnostic Trouble Code (DTC)s. The impact and pressure sensors do basic self-tests and faults are reported by the RCM.

The RCM drives the airbag warning indicator through FlexRay. When the warning indicator fails, a DTC is recorded and a warning tone is sounded in place of the indicator if a further fault occurs. In the event of an impact, the RCM records certain data which can be accessed through the diagnostic connector.

A sensor in the RCM provides confirmation of an impact to verify when airbag and pretensioner activation is necessary. A roll-over sensor monitors the lateral attitude of the vehicle. Various firing strategies are employed by the RCM to make sure that during an accident only the appropriate airbags and pretensioner are deployed. The firing strategy used also depends on the inputs from the seatbelt buckle switches.

An energy reserve in the RCM makes sure there is always a certain amount of electric energy available. The electric energy is available for the total time of 150 milliseconds when the power supply from the ignition circuit is disrupted during an impact. The stored energy is sufficient to produce deployment signals for the driver airbag, the passenger airbag and the seatbelt pretensioner.

When in Power Mode 6 (ignition ON), the RCM does a self-test and then does cyclical monitoring of the system. When a fault is detected, the RCM stores a related DTC and illuminates the airbag warning indicator. The faults can be retrieved by Jaguar Land Rover (JLR) approved diagnostic equipment. When a fault that could cause a false fire signal is detected, the RCM disables the respective firing circuit and keeps it disabled during an impact event.

DRIVER AIRBAG

NOTES:

• RHD vehicle is shown, LHD vehicle is similar.
• Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The driver airbag is located in the center of the steering wheel. The driver airbag provides head and chest protection for the driver when deployed during a front or rear impact.

Lines, molded into the inner surface of the airbag cover, provide weak points that split open in a controlled manner when the airbag deploys. The driver airbag has a single stage inflater with 1 connection.

PASSENGER AIRBAG

NOTES:

• RHD vehicle is shown, LHD vehicle is similar.
• Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The passenger airbag is located in the instrument panel, behind the upper glovebox. The passenger airbag provides head and chest protection for the passenger when deployed during a front or rear impact.

The top of the passenger airbag is attached to a channel chute underneath the top pad of the instrument panel. Doors in the top of the channel chute are forced open and split the top pad when the airbag deploys.

On all vehicles except NAS market, the passenger airbag has a single stage inflater. On NAS market vehicles the passenger airbag has a 2 stage inflater.

SIDE AIRBAGS

NOTES:

• RHD vehicle is shown, LHD vehicle is similar.
• Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The side airbags are attached to the outside of each front row seat backrest frame, under the backrest cover. The side airbags provide protection for the thorax, rib and pelvis when deployed during a side impact.

Each side airbag consists of a folded airbag and an inflater in a soft cover/wrapper. The airbag deploys and fills within a deployment chute integrated into the seat trim, and splits open the airbag deployment seam in the backrest cover.

IMPACT SENSORS AND PRESSURE SENSORS

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

1. Right pressure sensor
2. Front side impact sensor (quantity 2)
3. Rear side impact sensor - (quantity 2) - vehicle with 5 doors only
4. Left pressure sensor
5. Front impact sensor (quantity 2)

The impact sensors are installed in the front and both sides of the vehicle. The 2 front impact sensors are attached to the front end carrier, behind the inboard edge of each headlamp. The 2 front side impact sensors are attached to the lower B-pillars, behind the pillar trim panels. The 2 rear side impact sensors are attached to the base of C-pillars, adjacent to the rear door latch strikers. The 2 rear side impact sensors are only equipped on the vehicles with 5 doors.

The impact sensors are accelerometers that allow the RCM to detect the sudden vehicle acceleration that occurs during an impact.

A pressure sensor is installed in each front door, attached to the door closing panels. The pressure sensors allow the RCM to detect any sudden pressure pulse that occurs in the front door during a side impact.

SEAT TRACK POSITION SENSOR - NAS MARKET ONLY

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The seat track position sensor allows the RCM to detect when the seat is forward of a given point on the seat track.

The seat track position sensor is equipped on the passenger side on NAS market only.

The seat track position sensor consists of a hall effect sensor attached to the seat frame. When in Power Mode 6 (ignition ON), the RCM supplies the sensor with power, and monitors the return current. When the seat frame moves forward, the sensor moves over the edge of the seat track, which changes the reluctance of the sensor. The change of current is detected by the RCM 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 seat track.

OCCUPANT MONITORING

Occupant detection sensor

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The occupant detection sensors are installed in the cushions of the front outer and center passenger seats (6 seats), between the foam padding and the cover. The sensor consists of a foil contact circuit, embedded in a plastic sheet.

Weight on the sensor reduces the resistance of the circuit, which is detected by the BCM/ GWM.

The occupant detection sensor has no interface with the SRS. The occupant detection sensor only provides an input to the BCM/ GWM for the seatbelt reminder function.

Occupant classification sensor - NAS market only

The occupant classification sensor is equipped on the NAS market vehicles.

PASSENGER AIRBAG DEACTIVATION WARNING INDICATOR

1. Front overhead console
2. Passenger airbag deactivation warning indicator

The passenger airbag deactivation warning indicator is installed in the front overhead console. When appropriate, the indicator illuminates to advise front seat occupants that the passenger airbag is disabled. Operation of the indicator is controlled by the RCM.

The RCM illuminates the indicator when:

• There is a fault with the passenger airbag firing circuit(s).
• The passenger airbag is disabled in the IPC and the front passenger seat is occupied.

AIRBAG WARNING INDICATOR

Operation of the airbag warning indicator in the IPC is controlled by a FlexRay message from the RCM. The RCM sends the signal to illuminate the airbag warning indicator when a fault is detected. The airbag warning indicator displays for approximately 6 seconds during the bulb check at the beginning of each ignition cycle.

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