Pedestrian protection function - GF91.60-P-1005CA

MODEL 207.3/4 with CODE U60 (Pedestrian protection)

Function requirements, general

Vehicle speed v = 25 to 55 km/h
Circuit 15R ON

The instrument cluster (A1) sends the vehicle speed on vehicles up to 31.5.13 via chassis CAN (CAN E) or on vehicles as of 1.6.13 via chassis CAN 2 (CAN E2), front SAM control unit with fuse and relay module (N10/1) and chassis CAN 1 (CAN E1) to the supplemental restraint system control unit (N2/10).

The status of circuit 15 is sent by the electronic ignition lock control unit (N73) via chassis CAN (up to 31.5.13) or via chassis CAN 1 (as of 1.6.13) to the supplemental restraint system control unit.

Pedestrian protection, general

The pedestrian protection function reduces the level of injury severity in the event of any collision with a pedestrian. The cavity between the engine hood and the components below is increased by the engine hood moving up suddenly in the area of the A-pillars. 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 (up to 31.5.13)
Function sequence for displaying warning messages

Function sequence for impact recognition

The Supplemental Restraint System control unit reads in the signals directly from the following sensors:

Left front bumper pedestrian protection sensor (B151/1)
Center front bumper pedestrian protection sensor (B151/2) (up to 31.5.13)
Right front bumper pedestrian protection sensor (B151/3)

Up to 31.5.13:

The pedestrian protection is actuated in accordance with the acceleration values measured by the bumper pedestrian protection sensors.

As of 1.6.13:

The pedestrian protection is actuated in accordance with the pressure values measured by the bumper pedestrian protection sensors.

The pedestrian protection can be actuated erroneously in collisions with other objects (e.g. pole, guide post or thick branches).

Function sequence for activating pedestrian protection

The engine hood is raised in the area of the A-pillars by s = 10 cm by means of the engine hood lifters.

To do so, the supplemental restraint system control unit actuates the following actuators on vehicles up to 31.5.13:

Left rear engine hood lifter (Y127/1)
Right rear engine hood lifter (Y127/2)

On vehicles as of 1.6.13, the following squibs are actuated:

Left active engine hood squib (R12/49)
Right active engine hood squib (R12/50)

The pyrotechnical engine hood lifters design is not reversible.

Shown with actuated pedestrian protection

Fig 1: Identifying Supplemental Restraint System Control Unit

Courtesy of MERCEDES-BENZ USA

Function sequence for resetting engine hood after actuation (up to 31.5.13)

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 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.

Function sequence for displaying warning messages

If the engine hood was not completely closed, a corresponding message will appear in the multifunction display (A1p13) of the instrument cluster. The supplemental restraint system control unit reads in the signals of the pedestrian protection Hall sensors directly and, on vehicles up to 31.5.13, sends the request to output a warning message via chassis CAN or, on vehicles as of 1.6.13, via chassis CAN 1, front SAM control unit and chassis CAN 2 to the instrument cluster.

Function schematic for electric pedestrian protection	MODEL 207.3/4 up to model year 2014 with CODE U60 (Pedestrian protection)	PE91.60-P-2054-97EAA
	MODEL 207.3/4 as of model year 2014 with CODE U60 (Pedestrian protection)	PE91.60-P-2054-97EAB
Overview of system components for supplemental restraint system		GF91.60-P-9996CAM