Pedestrian Protection System: Description and Operation

GF91.60-P-1005FL Pedestrian Protection Function
- with CODE (U60) Pedestrian protection

Function requirements, general
^ Vehicle speed less than 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 electronic ignition lock control unit (N73) transmits the circuit 15 status to the supplement restraint system control unit via the chassis CAN.

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 comprises the following partial functions:
^ Function sequence for impact sensing
^ Function sequence for activating pedestrian protection
^ Function sequence for resetting engine hood after actuation

Function sequence for impact sensing
The supplemental restraint system control unit 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 can be actuated inadvertently in collisions with other objects (e.g. pole, guide post or thick 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)

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:
- Right engine hood contact switch (S62/42)
- Left engine hood contact switch (S62/43)

The supplement restraint system control unit reads in the signals from the contact switches.

If the engine hood was not fully closed, a corresponding message is output in instrument cluster. The output request for the message is transmitted by the supplement restraint system control unit to the instrument cluster via the chassis CAN.

The engine hood contact switch 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