Overview
This document contains the following information:
General
Function requirement
Triggering Supplemental Restraint System (SRS)
General
The SRS evaluates various input factors and deploys the corresponding restraint equipment in the event of an accident.
Function requirement
Circuit 15R on
Triggering Supplemental Restraint System (SRS)
The restraint equipment is actuated depending on:
Type and severity of the impact
Status of seat belts (fitted or not fitted)
Occupation of front passenger seat
In the following table, component parts marked with "X" are those that can be ultimately triggered for the respective accident scenarios:
Frontal impact | Side impact | Rear impact | Rollover | |
Driver airbag | X | - | - | - |
Passenger airbag | X | - | - | - |
Kneebag | X | - | - | - |
Front side airbag | - | X | - | - |
Rear passenger compartment side airbag (vehicles with side airbag in the rear) | - | X | - | - |
Cushionbag (vehicles with reclining rear seat) | X | - | - | - |
Window airbag | X | X | - | X |
Front ETR | X | X | X | X |
Rear emergency tensioning retractor | X | X | X | X |
Front seat belt end-fitting tensioner (Canada version or USA version) | X | - | - | - |
Front seat belt force limiter (Canada version, USA version or Japan version) | X | - | - | - |
PRE-SAFE® Impulse (vehicles with driver seat belt buckle with integrated tensioning function) | X | - | - | - |
PRE-SAFE® Impulse side (vehicles with PRE-SAFE® Impulse side) | - | X | - | - |
Gas generator inerting system (vehicles with alternative refrigerant and spark-ignition engine) | X | - | - | - |
12 V on-board electrical system battery pyrofuse (hybrid vehicles) | X | - | - | - |
Pyrofuse, circuit 30c (vehicles with 48 V technology, hybrid or electric vehicles) | X | X | X | X |
The following conditions are taken into account in the case of frontal impact:
Position of driver and front passenger seat (Canada version or USA version):
The SRS decides the trigger point of the driver and front passenger airbag depending on the position of the front seats.
The position of the front seats is recorded by a sensor at the guide rail of each front seat.
Front passenger seat occupancy status:
Front passenger seat unoccupied: The SRS does not deploy any restraint equipment on the front passenger side.
Child seat detected on front passenger seat and seat belt not fastened: The SRS does not deploy any restraint equipment on the front passenger side.
Child seat detected on front passenger seat and seat belt fastened: The SRS triggers the seat belt tensioner on the front passenger side.
Person detected on front passenger seat and seat belt not fastened: The SRS triggers the front passenger airbag.
Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the SRS does not deploy any seat belt relevant restraint equipment on the driver or front passenger side.
Status of seat belt buckles in rear:
If the seat belt is not fastened, the SRS does not deploy any restraint equipment in the rear passenger compartment.
The following conditions are taken into account in the event of a side impact:
Front passenger seat occupancy status:
Front passenger seat unoccupied: The SRS does not deploy any restraint equipment on the front passenger side.
Child seat or person detected on front passenger seat and seat belt not fastened: The SRS does not trigger the seat belt tensioner on the front passenger side.
Driver seat belt buckle status:
If the seat belt is not fastened, the SRS does not trigger the seat belt tensioner on the driver's side.
Status of seat belt buckles in rear:
If the seat belt is not fastened, the SRS does not trigger the seat belt tensioner in the rear passenger compartment.
The following conditions are taken into account in the event of a rear impact:
Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the SRS does not deploy any restraint equipment on the driver or front passenger side.
Status of seat belt buckles in rear:
If the seat belt is not fastened, the SRS does not deploy any restraint equipment in the rear passenger compartment.
The following conditions are taken into account in the event of a vehicle rollover:
Driver/front passenger seat belt buckle status:
If the seat belt is not fastened, the SRS does not deploy any restraint equipment on the driver or front passenger side.
Status of seat belt buckles in rear:
If the seat belt is not fastened, the SRS does not trigger the seat belt tensioner in the rear passenger compartment.
The status of the seat belts (fastened or unfastened) is recorded by a switch in the respective seat belt buckle.
With two-stage airbags, their deployment can be regulated.
Vehicles with alternative refrigerant and spark-ignition engine
In the event of a severe frontal impact, the refrigerant lines of the air conditioning system may be damaged. The leaking refrigerant together with the ambient air forms a combustible mixture. The inerting system ensures that this refrigerant/air mixture is kept separated from the hot engine parts. The hot engine parts are also effectively cooled. The inert gas argon is stored in the inerting system's gas cylinder. The targeted release of inert gas at the appropriate hot spots can counteract the potential ignition of the refrigerant/air mixture.
Vehicles with 48 V technology, hybrid or electric vehicles
In the event of an accident, the electric lines and components may be damaged. To avoid a fire hazard caused by a short circuit, the following pyrofuses are deployed:
Pyrofuse on battery terminal of on-board electrical system battery (hybrid vehicles): Disconnects the battery line from the rest of the on-board electrical system.
Pyrofuse 48 V or high voltage components: Disconnects the control terminal line (circuit 30 c). This shuts off the respective system.
Function schematics | |||
Function schematic, trigger Supplemental Restraint System | Model 213, 238, 257, 290 as of model year 2021 | ||
Model 118, 177, 247 | |||
Model 167Model 293 | |||
Subsystems | |||
Front passenger seat seat occupancy recognition, basic function | |||
Control units | |||
Supplemental restraint system control unit, basic function | |||
Components | |||
Inerting system, basic function | Model all (CAR) | ||
Seat belt end-fitting tensioner, basic function | Model all (CAR) | ||
Seat belt buckle switch, basic function | |||
Seat position Hall sensor, basic function | Model all (CAR) | ||
Pyrofuse, basic function | Model all (CAR) | ||
Seat belt tensioner, basic function | |||
Driver airbag, basic function | |||
Front passenger airbag, basic function | |||
Side airbag, basic function | |||
Window airbag, basic function | |||
Knee airbag, basic function | |||
Cushionbag, basic function | Model 167 |