Design [2 of 4]
Front impact sensor
The front impact sensors are used to provide the supplemental restraint system module (SRS) with advance information about the collision pulse. This enables the control module to determine more accurately the components to be activated.
The front impact sensors have integrated logic which transmits acceleration data to the supplemental restraint system module (SRS) in the same way as the side impact sensors.
In the event of a collision, the control module calculates the acceleration data from the front impact sensors and the internal sensors of the control module to check if the damage is sufficiently great to deploy the front impact protection.
In the event of a front impact sensor fault, a fault signal is sent to the control module, which generates a diagnostic trouble code. A trouble code is also generated if there is faulty communication between the control module and any of the front impact sensors. Each front impact sensor has a serial number that is used to check that the right front impact sensor is installed.
If one or both of the front impact sensors stops functioning, the control module uses the internal acceleration sensor to determine when the impact protection should be deployed.
Data is transmitted on the same cable used for power supply. There is a signal/power supply cable to each front impact sensor and a ground cable.
The two front impact sensors are behind the left and right-hand headlamps.
Belt retractor sensor (USA/CDN only)
The belt retractor sensor monitors the status of belt extension.
The belt retractor sensor sends information on the status of belt extension to the control module in real time. The control module then analyzes the obtained values and uses the results so that the belt force limiter can optimize belt force for the person occupying the seat.
There are two belt retractor sensors in the vehicle - one on the driver's side belt retractor and one on the front passenger side belt retractor.
Data is transmitted on the same cable used for power supply. There is a signal/power supply cable for each belt retractor sensor as well as a ground cable.
The adaptive belt force limiter, belt retractor, belt retractor sensor and belt tensioner are mounted in a unit. If there is a fault in any of these components, the entire unit must be replaced.
Seat position sensors (USA/CDN only)
The seat position sensor is used to determine the size of the person sitting on the seat. There are two seat position sensors in the vehicle - one under the driver's seat and one under the front passenger seat. The seat position sensors are directly connected to the supplemental restraint system module (SRS). The seat position sensors have separate signal cables to the control module and a common ground.
The seat position sensors comprise a Hall sensor that changes current strength based on the position of the seat. The seat position sensor has two classifications - small person or large person. Small person indicates that the seat is approx. 10 cm (4 in) or less from the front-most seat position. All other positions are classified as large person.
This information is used by the function for adaptive seatbelt force limiting.
Switch on/off, front passenger airbag (not USA/CDN)
With the switch it is possible to activate or deactivate the airbag for the front seat passenger.
The switch is located on the side of the instrument panel, on the passenger side. The switch is only accessible when the front side door on the passenger side is open.
The ignition key is used to change the position of the switch. When the switch is in position "OFF", all steps for the passenger airbag are deactivated and warning light airbag passenger (PAD) is lit.
When the switch is in position "ON", the passenger airbag is activated and warning light activated airbag passenger (PAE) is lit.
When the switch position is moved between "OFF" and "ON", two Hall sensor sense in which position the switch is. The Hall sensors for the switch are directly connected to the Supplemental restraint system module (SRS).
Each Hall sensor is separately connected to the control module. The signal that is sent from the Hall sensors consists of two different current levels depending on which position the switch is in.
If the signal from the Hall sensor cannot be interpreted correctly, a diagnostic trouble code is generated and the control module may, depending on the problem, choose to deactivate the passenger airbag.
If the passenger airbag is deactivated then warning light airbag passenger (PAD) and SRS-warning light are lit, and a text message is shown in the Driver information module (DIM). If a problem is detected and the passenger airbag is not deactivated, instead warning light activated airbag passenger (PAE) and the SRS-warning light are lit, and a text message is shown in the Driver information module (DIM).
Note! The activating switch, on/off, for the front passenger airbag and occupant weight sensor (OWS) must not be installed in the vehicle together.
Occupant weight sensor (OWS) (USA/CDN only)
The occupant weight sensor (OWS) consists of three interactive components:
- The pressure sensor, installed under the front passenger seat.
- Belt force sensor, mounted in the seat frame on the outside of the front passenger seat.
- Occupant weight sensor module, installed under the front passenger seat.
The pressure sensor and occupant weight sensor are linked via a hose. The pressure sensor registers the pressure the seat cushion is exposed to, for example when someone is sitting in the seat.
Information from the seat belt force sensor is also used to ensure the good performance of the system. The seatbelt force sensor informs the occupant weight sensor module what force the belt is tensioned with. This is done because the pressure measured by the pressure sensor can be affected by the passenger fastening the seatbelt tightly. This means that the passenger exerts greater pressure on the seat than during normal seatbelt use. The passenger is then interpreted as being heavier than he or she is.
Using information from both the pressure sensor and the seat belt force sensor, the occupant weight sensor module carries out calculations and classifications of what is affecting the system. This forms the basis for the recommendation that is communicated to the supplemental restraint system.
The occupant weight sensor (OWS) transmits continuous signals on the local controller area network (CAN), which the supplemental restraint system module (SRS) and occupant weight sensor (OWS) are connected to. If the occupant weight sensor (OWS) does not function correctly the supplemental restraint system module (SRS) will:
- disable the front passenger airbag
- light the passenger airbag warning lamp (PAD) in the roof console
- light the SRS (supplemental restraint system) warning lamp and display the alert message in the driver information module (DIM).
If a fault occurs in any of the components the following should be noted:
- The pressure sensor and occupant weight sensor module must be replaced at the same time
- The seat belt force sensor is replaced separately.
Note! The activating switch, on/off, for the front passenger airbag and occupant weight sensor (OWS) must not be installed in the vehicle together.
Adaptive seatbelt force limiter (USA/CDN only)
Warning! Never use an ohmmeter or similar tool to test airbags, inflatable curtains adaptive seatbelt limiters, adaptive steering column or seat belt tensioners. Disconnect airbags, inflatable curtains adaptive seatbelt limiters, adaptive steering column or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.
The adaptive belt force limiter improves the seat belt function in the event of a head-on collision when the airbag has been deployed. There are two adaptive belt force limiters in the car. These are located in top of the belt retractors, positioned at shoulder height on the driver's and front passenger seat belts.
The adaptive seatbelt force limiters are electrically separated from each other. The adaptive seatbelt force limiters have a pyrotechnic charge which adapts the seatbelt force to a lower level against the chest on activation.
The adaptive belt force limiter, belt retractor, belt retractor sensor and belt tensioner are mounted in a unit. If there is a fault in any of these components, the entire unit must be replaced.
The adaptive belt force limiter and lap belt tensioner use the same connections on the supplemental restraint system module (SRS). Thus, they cannot be connected at the same time in the vehicle.