Land Rover Discovery: Pedestrian Protection System / Description and Operation

COMPONENT LOCATION

CAUTION:

Jaguar Land Rover (JLR) is aware that some customers have requested that the pedestrian protection airbag cover be painted in an alternative color. Please note that Retailers are advised that the pedestrian protection airbag should not be painted in alternative colors as this is not an approved condition for the system.

1. Right front pressure sensor
2. Pressure tube
3. Left front pressure sensor
4. Pedestrian protection system airbag
5. Restraints Control Module (RCM)

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.

CAUTION:

Jaguar Land Rover (JLR) is aware that some customers have requested that the pedestrian protection airbag cover be painted in an alternative color. Please note that Retailers are advised that the pedestrian protection airbag should not be painted in alternative colors as this is not an approved condition for the system.

For additional information, refer to: Supplemental Restraint System Health and Safety Precautions (100-00 General Information, Description and Operation).

The pedestrian protection system is designed to protect pedestrians from impacts with the base of the windscreen using an airbag mounted within a cover at the trailing edge of the hood.

The Pedestrian protection system comprises:

• Two pedestrian protection system pressure sensors.
• A pedestrian protection system pressure tube.
• A pedestrian protection system airbag.
• The Restraints Control Module (RCM).

DESCRIPTION

PRESSURE SENSORS

NOTE:

It is not possible to replace the pressure sensors or pressure tube as individual components, the sensors and tube are supplied as a single component.

The two pressure sensors are mounted on the right and left hand side of the front bumper. They are connected to each end of pressure tube which is held in position by a 3 piece foam covering mounted on the pedestrian rail.

The pressure sensors have the characteristics as follow:

• Transmission of differential pressure data.
• Transmission of status data during start-up.
• Power-on sensor self-test.
• Parity checksum to ensure safe data transmission.

Each pressure sensor is hardwired to the Restraints Control Module (RCM).

PRESSURE TUBE AND PRESSURE TUBE RAIL

1. Pressure tube rail
2. Pressure tube

The pressure tube has a visible blue mark at it's mid point that indicates the tube is installed symmetrically The pressure tube rail acts as a reaction surface for the silicon tube, such that the tube is compressed against it during a frontal impact

AIRBAG

The airbag is contained in a housing and cover. The cover is attached to the airbag with two tethers, and is designed to form part of the airbag system.

This helps to spread the load across the airbag and thus reduces the airbag volume required. This helps reduce the airbag obscuration of the driver's vision.

OPERATION

The pedestrian protection system is active at vehicle speeds between 25 to 50 km/h (15 to 31 mph). If there is an impact on the front bumper of sufficient force, an airbag of 110 liters is deployed in 50 to 60 milliseconds.

Airbag deployment is triggered by pressure sensors mounted on either side of the front bumper. The pressure sensors are attached to each end of a pressure tube which is mounted on the inside of the front bumper. An impact creates a pressure pulse in the pressure which is detected by the two pressure sensors. The pressure senors transmit a digital status signal to the Restraints Control Module (RCM) which deploys the airbag if the operating parameters are met.

CONTROL DIAGRAM

A = HARDWIRED

1. Restraints Control Module (RCM)
2. Pedestrian protection system airbag
3. Ground
4. Power supply
5. Left front pressure sensor
6. Right front pressure sensor

Pedestrian Protection System Pedestrian Protection System Airbag (G2158917) / Removal and InstallationPedestrian Protection System / Diagnosis and Testing

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