Part 2

Adaptive steering column (USA/CAN only) (Continued)

Warning! Never use an ohmmeter or similar tool to test airbags, inflatable curtains adaptive belt force limiters, adaptive steering column or belt tensioners. Disconnect airbags, inflatable curtains, adaptive belt force limiters, adaptive steering column or belt tensioners before testing them. Failure to do so may result in accidental deployment, which in turn could result in serious injury or death.

When the impact protection in the adaptive steering column is deployed, a pin is triggered that makes the steering column more deformable. In the event of a severe impact, it will possible to press the steering wheel toward the dashboard to a greater degree than if the steering column were rigid.
Steering is not affected by the deployment of the pin. The pin is deployed by a pyrotechnical charge and is located in the center of the steering column. The impact protection system in the adaptive steering column only deploys if the driver is wearing the seat belt and when the airbag is deployed. The entire steering column must be replaced if the impact protection system in the adaptive steering column has deployed.

Side impact air bags

The two front seat belt buckles have Hall sensors and are connected to the SRS module. These connections are electrically separated from each other.
In some markets, each rear belt buckle also contains a Hall sensor, which is also connected to the supplemental restraint system module (SRS). These connections are electrically separated from each other.
The Hall sensor detects whether the belt is fastened in the buckle and sends information on belt detection to the Supplemental restraint system module (SRS). Information on belt detection is used to adapt the deployment level of airbags and belt tensioners. If a fault is detected in the belt buckles or their connections, there could also be adaption to this depending on the type of fault.

Belt tensioners

USA/CAN

Warning! Never use an ohmmeter or similar tool to test airbags, inflatable curtains, adaptive belt force limiters, adaptive steering column or belt tensioners. Disconnect airbags, inflatable curtains, adaptive seat belt limiters, adaptive steering column or belt tensioners before testing them. Failure to do so may result in accidental deployment, which in turn could result in serious injury or death.

Depending on the market, the vehicle may have up to six belt pretensioners. Five of these are located at floor level - one for each belt retractor - two in the front (1 and 2) and three in the backseat (3, 4, and 5).
In some markets, there is also a belt tensioner (6) located in the belt anchorage waist-high at the driver's seat.
The belt tension contains a pyrotechnical charge that tensions the belt upon deployment.
The belt tensioner tensions the seat belt to reduce the forward movement of the body. This also reduces the forces on the chest from the airbag and seat belt.
The supplemental restraint system module (SRS) determines whether to deploy the respective belt tensioner based on whether the seat belt is in use. The belt tensioner will not be deployed if the seat belt is not fastened. If the seat belts are fastened and seat belt indication in the front seat belt buckles does not function, the belt tensioners will be deployed anyway. Rear belt tensioner deployment is market dependent.
The belt tensioner consists of a pyrotechnical charge and a cylinder with a piston. The piston is connected to a steel cable which is secured to the seat belt retractor. When the control module deploys the belt tensioner, the piston is forced downward by the expanding gas. The piston pulls in the steel cable which retracts the belt.
For USA/CAN: the adaptive belt force limiter, belt retractor, and belt pretensioner are mounted in a unit. If there is a fault in any of these components, the entire unit must be replaced.

Adaptive seatbelt force limiter

Warning! Never use an ohmmeter or similar tool to test airbags, inflatable curtains adaptive belt force limiters, adaptive steering column or belt tensioners. Disconnect airbags, inflatable curtains, adaptive belt force limiters, adaptive steering column or belt tensioners before testing them. Failure to do so may result in accidental deployment, which in turn could result in serious injury or death.

The adaptive belt force limiters improve the function of the seat belt in the event of a head-on collision that triggers airbag deployment. There are two adaptive belt force limiters in the vehicle. These are integrated in the belt retractors of the driver and front passenger seat and sit at floor level. The two adaptive belt force limiters are electrically separated from each other. They have a pyrotechnical charge that upon deployment reduces belt force to reduce the forces against the chest.
The adaptive seatbelt force limiter, seat belt reel, seat belt (inertia) reel sensor and seat belt tensioner are installed in a single unit. In the event of a fault in any of these the whole unit must be replaced.

Seat position sensor (USA/CAN only)

The seat position sensor can be used to classify whether a small or large person sitting in 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 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.
For collision purposes, this information is used to optimize the function of adaptive belt force limitation and the front passenger airbag.

SRS indication

The supplemental restraint system module (SRS) continuously checks the system. A diagnostic trouble code (DTC) is stored and an SRS indication is made.
SRS indication is accompanied by a text message in the Driver information module (DIM), partly through:
- an SRS warning lamp
- a general warning lamp
The lamps light depending on how serious the fault is: Information about which lamp should be lit is transmitted by the supplemental restraint system module (SRS) on the controller area network (CAN).
The SRS warning lamp lights when the ignition is switched on. If no faults are registered by the control module, either internally or from the sensors, wiring or igniters, a signal is transmitted on the controller area network (CAN) to the driver information module (DIM) confirming that the SRS warning lamp can be switched off. If no faults are detected when the ignition is switched on, the lamp will remain lit for a few seconds. The lamp goes out when the system has been checked and is operating without faults.
The control module has an EEPROM memory which retains data about diagnostic trouble codes (DTCs) even when the battery has been disconnected.
The driver information module (DIM) continuously indicates to the supplemental restraint system module (SRS) the function of the SRS warning lamp. If the lamp stops working, the general warning lamp lights up and a message is displayed.

Note! If a diagnostic trouble code is stored because the resistance in an SRS ignition cable is too high or too low, it is important that the resistance of the SRS ignition cable is not measured when the collision protection system is connected. Special tools with the same resistance as the collision protection system must be used for fault-tracing.

Front passenger airbag indication

To indicate status of airbag passenger, the vehicle is equipped with two warning lights. The lights are located in the roof panel and are directly connected to the Supplemental restraint system module (SRS)
The supplemental restraint system module (SRS) turns the warning lights on or off depending on whether the front passenger airbag is deactivated or not.
If there is a front passenger airbag switch installed (market-dependent) and it is used to deactivate the airbag, the front passenger airbag warning light (PAD) (1) is lit.
The warning light turns off when the airbag is activated again and then warning light activated airbag passenger (PAE) is lit instead (not USA/CAN) (2).
If an occupant weight sensor (OWS) is installed (market-dependent), the warning light airbag passenger (PAD) is lit when the airbag is deactivated.
The warning light turns off when the airbag is activated again. In these cases, the warning light activated airbag passenger (PAE) (not USA/CAN) will never be lit.
Reason the passenger airbag warning lamp (PAD) lights could also be:
- malfunction of the switch for the front passenger airbag, causing the supplemental restraint system module (SRS) to disable the front passenger airbag.
- malfunction of the occupant weight sensor (OWS), causing the supplemental restraint system module (SRS) to disable the front passenger airbag.
- other problems that affect function of the SRS-system.

Sensor-CAN

Terminating resistor in Supplemental restraint system module (SRS) and Closing velocity module (CVM).
Occupant weight sensor (OWS), only USA/CAN.
A number of control modules communicate, in addition to via ordinary network (CAN-HS/CAN-MS), also via a separate local network, sensor-CAN, to exchange information (sensor data).

These control modules are:
- Supplemental restraint system module (SRS)
- Occupant weight sensor (OWS) (USA/CAN only)
- Forward Sensing Module (FSM)
- Closing velocity module (CVM)
- Brake control module (BCM)
Supplemental restraint system module (SRS) acts as main node for sensor-CAN-net. The speed on sensor-CAN is the same as for HS-CAN, 500 kbit/s.
All control modules on sensor-CAN, except Occupant weight sensor (OWS), are also connected to HS-CAN. All diagnosis and software downloads take place via HS-CAN.
The Occupant weight sensor (OWS) is diagnosed by the Supplemental restraint system module (SRS).
For more information on the CAN-net, see: Design and Function - CAN-net.
There are control modules on sensor-CAN that do not send any signals on the network and thus other control modules do not set any fault codes for "signal missing" for these control modules. There are also control modules on sensor-CAN that do not receive any signals on the network and thus control modules do not set any fault codes for "signal missing" for other control modules on sensor-CAN.

Deploying airbags/belt tensioners
The supplemental restraint system is extremely advanced. It is able to adapt airbag and belt tensioner deployment to suit the specific circumstances of a collision. In general, it is extremely unlikely that all airbags and belt tensioners will be deployed in the same accident. It is possible that only one airbag or belt tensioner is deployed. This is determined by the supplemental restraint system module (SRS) based on the forces that arise during the collision.
If the control module deploys the front airbags, all stages will always be activated. By varying the time between the deployment phases, the inflation of the airbag is more gentle for a low speed collision.

Deployment levels for impact protection upon head-on collision
The table below shows how the SRS system usually reacts in the event of a head-on collision.
Level 1= Low speed collision
Level 5 = Severe collision

Deploying the side impact protection system
The table below shows how the SRS system usually reacts in the event of a side-on collision.

Deployment levels for impact protection upon rear-end collision
The table below shows how the SRS system usually reacts in the event of a rear-end collision.