The multiple restraint system 6 (MRS) is a continuous enhancement of the multiple restraint systems in MINI vehicles.
The MRS has the following tasks:
The following components are described for the multiple restraint system (see also national version):
All inflator assemblies and sensors are connected directly to the MRS control module.
The MRS control module evaluates the data from the sensors.
In the event of a collision, the MRS control module decides whether seat belt tensioner and airbag triggering is required and which airbags have to be triggered.
Two acceleration sensors are fitted in the MRS control module.
The longitudinal acceleration sensor detects a frontal or rear-end collision.
The lateral-acceleration sensor detects a side-on collision.
An ignition capacitor is fitted in the MRS control module. If the power supply is interrupted in a collision, the ignition capacitor serves as an energy reserve for the MRS control module.
The 2 airbag sensors are pressure sensors. The airbag sensors are fitted in each of the inner door panels.
The airbag sensor consists of the following components:
if the door outer skin is pressed inwards in a side-on collision, the door interior is reduced in size. This increases the pressure in the door interior. This increase in pressure is measured by the pressure sensor. The measured pressure values are digitized in the electronic module. The electronic module sends a message to the MRS control module (cyclical message transfer). The message is evaluated in the MRS control module.
The 2 airbag sensors in the left-hand and right-hand B-pillars each contain a lateral-acceleration sensor and a longitudinal acceleration sensor.
The longitudinal acceleration sensor detects a frontal or rear-end collision.
The lateral-acceleration sensor detects a side-on collision.
The belt buckle switches indicate whether the seat belts have been fastened or not. The belt buckle switches are supplied with voltage by the MRS control module. The current consumption of the switch is the signal for the switch position (seat belt fastened or not fastened). The belt buckle switches are monitored permanently as of terminal R On.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Belt buckle switch for passenger belt |
2 |
Belt buckle switch for rear right seat belt |
3 |
Comb connector |
5 |
Belt buckle switch for rear left seat belt |
5 |
Belt buckle switch for driver belt |
|
|
K CAN |
Body CAN |
Terminal 31 |
Terminal 31 |
Terminal R |
Terminal R |
MRS |
MRS control module |
The passenger seat occupation detection detects whether the seat is occupied or not.
The seat occupation mat consists of conductor tracks with pressure sensors. The conductor tracks are connected to the electronic evaluation unit.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Seat occupation mat with pressure sensors |
2 |
Electronic evaluator |
With a load applied by a weight as of approx. 12 kilograms, the seat occupation mat changes its resistance. The signal is sent across a direct line to the MRS control module. The signal is only required for the seat belt warning.
If the front passenger's seat is detected as occupied without the belt buckle switch sending a signal, a seat belt warning is issued.
Triggering of the seat belt tensioner on the passenger's side depends on the status signal of the belt buckle switch (seat belt fastened or nor fastened). If the seat belt is inserted in the belt buckle switch, the seat belt tensioner is also triggered (only with frontal / rear-end collision).
In the switch position ”OFF”, the following airbags on the passenger's side are not inflated: Front passenger's airbag and side airbag.
The indicator lamp for passenger airbag deactivation (passenger airbag off lamp) lights up.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Indicator lamp for passenger's airbag deactivation |
2 |
Switch for passenger's airbag deactivation |
3 |
Comb connector |
|
|
K CAN |
Body CAN |
Terminal 31 |
Terminal 31 |
Terminal R |
Terminal R |
MRS |
MRS control module |
For vehicles without a switch for passenger's airbag deactivation, there is a retrofit kit (optional extra 5DA ”Passenger's airbag deactivation”).
The switch is operated using the key integrated in the remote control.
The CAS control module delivers input signals with regard to terminal voltage (e.g. terminal R On). The MRS control module is supplied with voltage by the CAS control module (as of terminal R).
When an airbag triggers, the DME or DDE switches off the electric fuel pump. The DME or DDE receives a message from the MRS control module.
The JBE handles activation of the central-locking drives. In the event of an accident with the corresponding severity, the central-locking system is unlocked.
The footwell module controls the interior lighting and exterior lighting. In the event of an accident with the corresponding severity, the interior lights and hazard warning lights switch on automatically.
The instrument cluster shows the visual seat belt warning and issues an acoustic seat belt warning.
The MRS control module activates the seat belt warning by means of a Check Control message.
The instrument cluster receives the status as of terminal R On from the MRS control module. With the corresponding status, a visual and acoustic seat belt warning is issued as of terminal 15 On.
The instrument cluster also contains the airbag warning lamp.
The instrument cluster is connected via the K-CAN with the MRS control module.
With maximum equipment, the safety system consists of the following firing circuits (see also national version):
The driver and passenger airbags reduce the risk of head injuries or injuries in the area of the occupants' chest in a frontal collision.
The driver's airbag is located under the impact pad of the steering wheel. The front passenger's airbag is built into the instrument panel above the glove compartment.
The side airbags reduce the risk of injuries to the occupants in the lap or torso area in the event of a side-on collision. The side airbag are fitted in the armrest side sections of the front seats.
The head airbag prevents direct contact of the head against the side structure or an obstacle entering the vehicle. The head airbag stretches continuously at head height from the A-pillar to the C-pillar.
After triggering, the shape and stability of the head airbag are maintained for a number of seconds. The head airbag deflates more slowly than the front and side airbags. This means that the head is protected for longer in the event of overturning.
Head airbags are fitted on the driver's side and passenger's side.
As a rule, the seat belt does not fully tighten around the body. The so-called ”belt slack” of the seat belt ensures that the occupants can move comfortably to an adequate degree. In the event of a frontal or rear-end collision, the pyrotechnic seat belt tensioner pulls the belt buckle a number of centimetres downwards. This tightens the seat belt simultaneously in the lap and shoulder region of the occupants.
The airbag warning lamp indicates the proper functioning of the multiple restraint system. The airbag warning lamp in the instrument cluster is activated by the MRS control module via the K-CAN.
The seat belt warning lamp is the visual seat belt warning. The visual seat belt warning tells the occupants to fasten their seat belts. The visual seat belt warning is started as of terminal 15 On.
The visual seat belt warning is displayed as follows:
If the indicator lamp for passenger airbag deactivation (passenger airbag off- lamp) lights up, the following airbags on the passenger's side are disabled: Front passenger's airbag and side airbag.
The passenger airbag off lamp is continuously monitored via the MRS control module. A fault in the power supply or a defective lamp is saved in the fault memory of the MRS control module. In this case, the airbag warning lamp is switched on.
Depending on the severity of the accident, the flow of fuel is also interrupted. The DME or DDE switches the electric fuel pump off.
In the event of a rollover, the roll bar extends, locks and thus secures the survival space for the vehicle occupants. There is a roll bar behind each of the rear seats. In the event of an accident with rollover, the sensor in the vehicle center satellite detects the vibration and sends the information ”activate roll bar” to the safety module. The information ”activate roll bar” is forwarded across the serial cable. In addition, the other satellites determine the severity of the accident. With the information ”activate roll bar” matching ”severity of the accident”, the roll bars are triggered. There are two possibilities to activate the roll bar: Triggering in the event of an accident and triggering for verification of function via the diagnosis (service functions)
The seat belts are the primary restraint system for all occupants.
To minimize the force in the chest area of the front-seat occupants in the event of a severe frontal collision, the front seat belts are equipped as series standard with belt tension limiters. The belt tension limiters ensure that the seatbelt strap has a defined flexibility as of a certain force. The risk of injury due to belt forces exerted on the body is reduced.
The following system functions are described for the multiple restraint system:
In addition to all inputs and outputs, the MRS control module also monitors the internal components (self-test). Possible faults are saved in the MRS control module. In the event of a system fault or a fault in a component, the airbag warning lamp lights up.
The MRS control module starts a self-test after the ignition has been switched on. During this time, the airbag warning lamp lights up (approx. 3 to 5 seconds). When the safety system is functional, the airbag warning lamp goes out.
If the instrument cluster receives no CAN message from the MRS control module, the airbag warning lamp lights up.
If the MRS control module has already detected a current or saved fault during the self-test or while the vehicle is being driven, the airbag warning lamp remains switched on.
If a fault is detected in the safety system, the operability of the safety system is partially maintained under the following conditions:
In the event of an internal fault in the MRS control module or power supply, the entire safety system is disabled (airbag warning and seat belt warning lamp light up, Check Control symbol in the LC display)
The MRS control module picks up every collision within an angular range of 360°.
The direction and severity of a collision are picked up by acceleration sensors in the MRS control module and by external acceleration sensors.
External acceleration sensors:
The MRS control module processes all the acceleration data. This determines the severity of the accident.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Front airbag sensor on passenger's side |
2 |
Front door airbag sensor on passenger's side |
3 |
B-pillar airbag sensor on passenger's side |
4 |
B-pillar airbag sensor on driver's side |
5 |
Front door airbag sensor on driver's side |
6 |
Front airbag sensor on driver's side |
K CAN |
Body CAN |
Terminal R |
Terminal R |
MRS |
MRS control module |
|
|
Comprehensive tests are used to set trigger thresholds for all possible types of accident.
These result in different trigger thresholds for activation of the following restraint systems (note national version):
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Front passenger's airbag (one-stage or two-stage, depending on national version) |
2 |
Front side airbag, passenger's side |
3 |
Seat belt tensioner, passenger belt |
4 |
Head airbag, passenger's side |
5 |
Comb connector |
6 |
Head airbag, driver's side |
7 |
Seat belt tensioner, driver belt |
8 |
Front side airbag, driver's side |
9 |
Driver's airbag (one- or two-stage, depending on national version) |
|
|
K CAN |
Body CAN |
Terminal 31 |
Terminal 31 |
Terminal R |
Terminal R |
MRS |
MRS control module |
The restraint systems are only triggered if 2 independent sensors simultaneously detect the corresponding threshold values.
For example, a frontal collision is detected via the longitudinal acceleration sensor in the B-pillar airbag sensor on the driver's side and the longitudinal acceleration sensor in the MRS control module. The MRS control module uses the data sent by the sensors to calculate the direction of the collision and the severity of the accident. Depending on the severity of the accident, the electric fuel pump is switched off.
Two examples (frontal collision and side-on collision) are used to illustrate the triggering of the various restraint systems:
When the restraint systems are triggered, certain data is written into a non-erasable data memory of the MRS control module. The data is relevant to accident research (no access for service).
If the restraint systems trigger, the MRS control module sends a message to other control modules. Depending on the severity of the accident, the relevant control modules perform the following functions:
For the seat belt warning, the signals of the 2 belt buckle switches (driver belt, passenger belt) are monitored separately.
If the seat occupation detection indicates that the passenger's seat is occupied, the passenger belt must also be inserted in the belt buckle. The seat belt warning then goes out.
The following situations are taken into account for output of a seat belt warning:
For the visual seat belt warning, the status signals of the 2 belt buckle switches (rear left and rear right seat belts) are monitored separately (note national version).
The status display or visual seat belt warning (seat belt fastened or not fastened, as the case may be) is displayed in the LC display of the instrument cluster separately for each seat belt.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Visual seat belt warning: seat belt on rear left not fastened |
2 |
Visual seat belt warning: seat belt in rear fastened |
The visual seat belt warning starts directly after the service requirement display, at the latest 5 seconds after terminal 15 On. The visual seat belt warning is switched on for 30 seconds.
With every change in state, the display duration (30 seconds) starts anew. Change in state i.e.:
The display can be cancelled at any time by briefly pressing the onboard computer button.
The following general data is provided for servicing the MRS:
Disconnecting the battery terminals
Caution: After disconnecting the battery terminals, wait 1 minute before starting work on the MRS safety system.
After disconnecting the battery terminals, 1 minute must be waited before starting work on the MRS safety system.
The waiting period ensures that the capacitors with the energy reserve of the system are completely discharged. This prevents inadvertent triggering of airbags or seat belt tensioners.
Checking the components of the multiple restraint system
Caution: Do not test components of the safety system with multimeters or other universal test devices.
Testing with a multimeter or other universal test tools can lead to accidental deployment and injuries. For system diagnosis, use only the BMW diagnosis system.
Caution: Do not connect any electrical test devices to the wire harness of the multiple restraint system.
Do not connect any electrical test devices to the wire harness of the multiple restraint system as long as the wire harness is connected to a component of the safety system. Accidental deployment and violation can occur.
Use exclusively the BMW diagnosis system for system diagnosis.
Caution: Check the safety system MRS after repairing damage caused by an accident.
After repairing damage caused by an accident, the MRS safety system must be checked using the BMW diagnosis system (even if this accident did not trigger a restraint system).
Fitting approved seat covers
Caution: only fit approved seat covers.
Do not fit seat covers, cushions or other objects on the front seats that have not been specially approved for seats with integrated side airbags. Do not hang articles of clothing, e.g. jackets, over the front seat backrests. This severely impairs or disables the airbag function.
Note: After 3 crash signals with triggering of the safety system, replace the MRS control module.
The MRS control module saves data in a non-erasable memory after a triggering of the safety system. After 3 crash signals, the data memory is full. The airbag warning lamp lights up. The MRS control module must be replaced.
Note: Deactivating the acoustic seat belt warning
The acoustic seat belt warning can be disabled by means of encoding. This does not affect a legally prescribed seat belt warning.
2-stage driver's airbag and passenger's airbag
The driver's and front passenger's airbag are each equipped with a 2-stage gas generator. Depending on the severity of the accident, the two level of the airbag are triggered with a delay.
The two stages of the gas generator enable a restraint function that is adapted the severity of each accident and prevents additional load on the occupants during the unfolding phase of the airbag.
Seat occupation mat, passenger
The passenger seat occupation detection detects whether the seat is occupied or not.
The seat occupation mat consists of conductor tracks with pressure sensors. The conductor tracks are connected to the electronic evaluation unit.
If the seat occupation mat is defective, the airbags on the passenger's side are automatically disabled (front passenger's airbag and side airbag). The indicator lamp for the passenger's airbag deactivation lights up.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Seat occupation mat with pressure sensors |
2 |
Electronic evaluator |
According to the regulations of the NHTSA (National Highway Traffic Safety Administration), a small child in the child restraint system specifically designed for the purpose on the front passenger's seat must be detected automatically.
On detection, the airbags on the passenger's side are automatically disabled (front passenger's airbag and side airbag). The indicator lamp for the passenger's airbag deactivation lights up.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Indicator lamp for passenger's airbag deactivation |
2 |
Seat occupation mat |
3 |
Comb connector |
|
|
K bus |
Body bus |
K CAN |
Body CAN |
Terminal 31 |
Terminal 31 |
Terminal R |
Terminal R |
MRS |
MRS control module |
|
|
If a person of adequate size sitting correctly (adolescent / adult) is detected, the airbag on the passenger's side are activated (front passenger's airbag and side airbag). The indicator lamp for the passenger's airbag deactivation does not light up.
In certain cases involving adolescents and adults, the front passenger's airbag can deactivate (indicator lamp for front passenger's airbag deactivation lights up). In these cases, the seat position must be can be changed until the indicator lamp for the front passenger's airbag deactivation goes out (front passenger's airbag and side airbag activated).
The seat occupation detection is based on evaluation of the applied surface pressure that is created when a load is applied. The distances of the surfaces and centres of gravity on the occupied seat cushion indicate whether an adolescent or adult or small child is in the child restraint system specifically designed for the purpose.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Applied surface pressure of an adolescent or adult |
2 |
Applied surface pressure of a child's seat |
Airbag front sensor, driver's side and passenger's side
The 2 front airbag sensors are longitudinal acceleration sensors. The sensors in the front on the left and right detect a frontal or rear-end collision.
Seating position sensor
According to the regulations of the FMVSS (Federal Motor Vehicle Safety Standard), a 5 %- woman must be distinguished from a 50 % man on the driver's seat.
The seating position sensor detects the airbag range designed for a person with regard to the seat adjustment in longitudinal direction.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Seating position sensor |
2 |
Seat rail (moveable) |
3 |
Seat rail (fixed) |
4 |
Magnet holder |
The seating position sensor is a Hall sensor and it is supplied with voltage via the MRS control module. The current intensity changes depending on the distance of the seat position switch to the magnet holder.
Index |
Explanation |
Index |
Explanation |
|---|---|---|---|
1 |
Seating position sensor |
2 |
Comb connector |
Terminal 31 |
Terminal 31 |
Terminal R |
Terminal R |
MRS |
MRS control module |
|
|
The signal of the seating position sensor also influences the delayed triggering of stage 2 of the gas generator (driver's airbag).
Visual and acoustic seat belt warning
As of terminal 15 On, a visual and acoustic seat belt warning is issued. The seat belt warning has a time limit (6 seconds).
The rest of the sequence for seat belt warning is identical to the seat belt warning in EURO vehicles.
Visual and acoustic seat belt warning
As of terminal 15 On, a visual and acoustic seat belt warning is issued. The seat belt warning has a time limit (6 seconds).
No liability can be accepted for printing or other faults. Subject to changes of a technical nature