Part 2

Design

Control module

Adaptive steering column (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.

When the adaptive steering column in the collision protection system is activated, a pin is deployed which makes the steering column longitudinally adjustable and thus collapsible. If the frontal collision exceeds a certain level the steering wheel is pressed into the dashboard to a greater degree than if the steering column were rigid.
The 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 collision protection system in the adaptive steering column only functions if the driver is wearing the seatbelt and if the airbag deploys. The entire steering column must be replaced if the collision protection system in the adaptive steering column has deployed.

Front airbags

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 airbags at the front of the vehicle are:
- driver airbag, 2 stage deployment
- front passenger airbag, 2 stage deployment.
The driver's airbag is located in the steering wheel. The passenger airbag is located above the glove compartment in the dashboard.
The front airbags have two ignition components each. These are electrically separated from each other. This means that the different ignition components have their own separate power supply and grounding points from the control module. Two power supply outputs are required from the control module for each airbag, one for each ignition component. This means that in total four pins on the control module, two power supply pins and two ground pins, are used for each airbag.
When activating the airbags, electrical signals are transmitted from the supplemental restraint system module (SRS) to the relevant airbag stage.

Stage 1
Stage 1 of the driver's airbag is pyrotechnic. In the event of deployment, the charge combusts and the gas which develops is blown into the airbag.
Stage 1 on the passenger airbag consists of a pyrotechnic component in combination with a reservoir which stores a gas. On activation the pyrotechnic charge and mixes with the stored gas. The gas mixture is blown into the airbag.

Stage 2
Stage 2 of the driver's and passenger airbags is pyrotechnical. In the event of deployment, the charge combusts and the gas which develops is blown into the airbag.
The pace of the airbag 2 stage activation is dependent on collision type and seat belt use. Both stages activate but in the event of a lesser impact, there is a greater time delay between stage 1 and stage 2. For more serious impacts the time delay is shorter between stages 1 and 2.

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.

Side impact air bags

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 vehicle four or five belt tensioners (depending on the market). Four of these are located at shoulder height - one for each belt retractor - two in the front (1 and 2) and two in the rear seat (3 and 4).

Note! The seat belt tensioners for the USA/CDN market (1a and 2a) are as illustrated above. The seat belt tensioners for other markets (not USA/CDN) (1b and 2b) are as illustrated above.

In some markets, there is also a belt tensioner (5) located in the belt anchorage waist-high at the driver's seat (not C30).
The belt tension contains a pyrotechnical charge that tensions the belt upon deployment.
The seat 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 seat belt tensioners based on whether the seat belts are being used. The seat belt tensioner will not be activated if the seat belt is not engaged. If the seat belt is fastened and the seatbelt indication does not function for the front seat belt buckles, the seat belt tensioners will be activated anyway. Rear seat belt tensioner activation 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/CDN: 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.

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.

Inflatable curtains

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.

There are two inflatable curtains connected to the supplemental restraint system module (SRS). Their connectors are electrically separated from each other.
The inflatable curtains are located in the roof between the A-post and C-post. They have only one igniter component each. The purpose of the curtain is to protect the head and parts of the upper body in the event of a side-on collision. The supplemental restraint system module (SRS) deploys the inflatable curtain on the side closest to the point of impact.
The inflatable curtain uses a pyrotechnic component in combination with a reservoir which stores a gas. In the event of deployment, the pyrotechnic charge combusts and mixes with the stored gas. The gas mixture inflates the curtain, which falls down and covers the door windows and B-post.

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.

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
- a yellow information 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 ignition cable is too high or too low, it is important that the resistance of the 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 troubleshooting.

Passenger airbag indication

Supplemental restraint system module (SRS) sends signals on the CAN-net to Central electronic module (CEM) about the airbag for passenger front is activated or not.
If Central electronic module (CEM) receives information that passenger airbag is activated, it sends signals on a directly connected cable to light warning light activated airbag passenger (PAE) (1).
It works in the same way if Central electronic module (CEM) receives information that the passenger airbag is deactivated, but then the signal to light the warning light airbag passenger (PAD) (2) is sent.
The lights are located in the overhead panel. Each light is on until Central electronic module (CEM) receives information that the status of the passenger airbag has been changed.
Depending on the market, if the switch for activating and deactivating the front passenger airbag is used to deactivate it, the passenger airbag disconnected (PAD) warning lamp lights.
The warning light goes off when the airbag is activated again and then warning light activated passenger (PAE) is lit instead.
If an occupant weight sensor (OWS) is installed (market-dependent), the passenger airbag warning light (PAD) lights when the airbag is deactivated.
The warning lamp goes out when the airbag is enabled.
If Occupant weight sensor (OWS) is installed, there is no warning light activated airbag passenger (PAE) installed.
Reason the passenger airbag warning lamp (PAD) lights could also be:
- communication problems between the supplemental restraint system module (SRS) and central electronic module (CEM)
- faulty function in the on/off switch for the front passenger airbag
- defective occupant weight sensor (OWS) function.

Seatbelt buckle

The two front seat belt buckles have Hall sensors and are connected to the SRS module. These connections are electrically separated from each other.
The Hall sensor detects whether the belt is engaged in the seat belt buckle or not and indicates this to the supplemental restraint system module (SRS). The information is used to set the activation level for airbags and seat belt tensioners. If a fault is detected in the seat belt buckles or in their terminals, an adjustment is made for this, depending on the type of fault.
The rear seat belt buckles can be connected (market dependent) to the central electronic module (CEM) which then transmits the status of the seat belt buckles to the SRS (supplemental restraint system) module via the controller area network (CAN). In the event of a fault in the rear seat belt buckles the seat belt tensioners will function as if the seat belts are fastened (market dependent).

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

Deployment levels for airbags/seat belt tensioners
The table below shows how the SRS system reacts in the event of a frontal impact.
Level 1= Low speed collision
Level 5 = Severe collision

Side airbag deployment
The table below shows how the SRS system reacts in the event of a side impact.