Pedestrian protection function

Function requirements, general

 Vehicle speed v = 25 to 55 km/h

 Circuit 15 ON

 The instrument cluster (A1) transmits information on the vehicle speed to the supplement restraint system control unit (N2/10) via the chassis CAN (CAN E).

The status of circuit 15 is sent by the electronic ignition lock control unit (N73) over chassis CAN to the supplemental restraint system control unit.

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Pedestrian protection, general

The pedestrian protection function reduces the level of injury severity in the event of any collision with a pedestrian. The space between the engine hood and the components below is increased by the engine hood moving up suddenly in the area of the A-pillar.

This space prevents the pedestrian from being hit directly by the components below the engine hood.

Pedestrian protection includes the following subfunctions:

 Function sequence for impact recognition

 Function sequence for activating pedestrian protection

 Function sequence for resetting engine hood after actuation

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Function sequence for impact recognition

The supplemental restraint system control unit directly reads in the signals from the following sensors.

- Left front bumper pedestrian protection sensor (B151/1)

- Center front bumper pedestrian protection sensor (B151/2)

- Right front bumper pedestrian protection sensor (B151/3)

The pedestrian protection is actuated according to the acceleration values measured

 The pedestrian protection may be actuated by mistake in a collision with other objects (e.g. pole, guide post or thicker branches).

Function sequence for activating pedestrian protection

The supplemental restraint system control unit activates the following actuators to raise the engine hood:

- Left rear engine hood lifter (Y127/1)

- Right rear engine hood lifter (Y127/2)

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Function sequence for resetting engine hood after actuation

The engine hood lifter is designed reversibly. After triggering, the engine hood can be returned manually to its initial position. For this purpose unlock engine hood and open completely. After closing the engine hood, resetting is completed.

Complete closing of the engine hood is detected by the following sensors:

- Engine hood switch pedestrian protection + ATA Hall sensor (A38/1)

- Pedestrian protection Hall sensor (B100)

The supplement restraint system control unit reads in the signals from the pedestrian protection Hall sensors.If the engine hood was not completely closed, the multifunction display (A1p13) of the instrument cluster shows a corresponding message. The output request for the message is sent by the supplement restraint system control unit to the instrument cluster over the chassis CAN.

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 The pedestrian protection Hall sensors only recognize whether the engine hood is completely closed. They do not recognize, whether the engine hood has been reset correctly.

After resetting the engine hood, the pedestrian protection function can be immediately activated again