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Home >> Volvo >> 2012 >> C30 R Design L5-2.5L Turbo VIN 67 B5254T7 >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Description and Operation >> Function

Function






Function

Checking the SRS system




When the ignition key is turned from 0 to I, II or III, the communication on the controller area network (CAN), the status of the internal functions in the supplemental restraint system module (SRS) (4/9) as well as all directly connected components are checked:
- airbags driver (8/30 and 8/61)
- airbags passenger (8/31 and 8/32)
- seat belt tensioners (8/33, 8/34, 8/55 and 8/56)
- seat belt tensioners lap driver (8/92) (only certain markets) (not C30)
- side impact sensors B-post (7/115 and 7/116)
- side impact sensors C-post (7/108 and 7/109) (not C30)
- side impact sensors (pressure sensors) doors (7/228 and 7/229) (only C30)
- inflatable curtains (8/66 and 8/67)
- SIPS bags (8/51 and 8/52)
- front impact sensor (7/178 and 7/179)
- front seat belt buckles (3/93 and 3/94)
- adaptive steering column (8/99) (only US)
- seat position sensor (3/255 and 3/256) (only USA/CDN)
- adaptive seat belt force limiter (8/128 and 8/129) (only USA/CDN)
- seat belt roller sensor (7/194 and 7/195) (only USA/CDN)
- switch on/off, front passenger airbag (3/157) (not USA/CDN)
- occupant weight sensor (OWS) (7/93) (only USA/CDN)
The supplemental restraint system module (SRS) transmits information via the controller area network (CAN) to the driver information module (DIM) (5/1) indicating that this test is in progress. The central electronic module (CEM) (4/56) also transmits the parameter values during the status check.
The driver information module (DIM) then lights the SRS warning lamp. The SRS warning lamp is lit while the supplemental restraint system (SRS) is being checked. When the supplemental restraint system (SRS) has been tested and no faults have been detected, the SRS warning lamp goes out.
If a fault is detected during the check it will be indicated in one of the following ways, depending on how serious it is:
- the SRS indicator lamp continues to light and a warning text is displayed in the driver information module (DIM).
- the general red warning light lights and a warning text is displayed in the driver information module (DIM).
- the general yellow warning lamp lights and a warning text is displayed in the driver information module (DIM).
The driver information module (DIM) continuously sends a signal via the CAN-network to the Supplemental restraint system module (SRS) with information about if the SRS-warning light is working or not. If the SRS-warning light stops working, the general red warning light is activated. If the CAN-communication between the Supplemental restraint system module (SRS) and Driver information module (DIM) stops, the general red warning light is activated and an associated warning text is shown on the display in the Driver information module (DIM). If the malfunctions disappear and the Driver information module (DIM) can send information again to the Supplemental restraint system module (SRS), and the status of the SRS-warning light is OK, the warning lights will return to normal function.

Side impact




In event of a side-on collision, the side impact sensors (7/108, 7/109, 7/115 and 7/116 for the S40/V50) and (7/115, 7/116, 7/228 and 7/229 for the C30), on the left and right-hand sides evaluate the force of the collision pulse.
If the collision pulse is powerful enough, the level of the acceleration signal from the side impact sensors will exceed the calculated activation level for the collision protection system in the supplemental restraint system module (SRS) (4/9).
The control module must also receive another signal, either from the acceleration sensors in the control module or another side impact sensor.
If the signal from the collision sensor meets the conditions for activation of the side impact airbags (8/51 and 8/52) and/or inflatable curtains (8/66 and 8/67), the control module sends a current pulse to those side impact airbags and/or inflatable curtains that are to be deployed. The side impact protection system will only be deployed on the side where the impact is registered.
The control module also transmits a collision signal on a directly connected cable to the central electronic module (CEM) (4/56) and the phone module (PHM) (16/60), so that these control modules can take certain actions.
A collision status signal is also sent to the phone module (PHM) and the central electronic module (CEM) via the controller area network (CAN).

Front-end collision (not USA/CDN)




In case of a frontal collision, a function called multi-point sensing is used. This means that the collision pulse is registered at several points. This function is integrated in Supplemental restraint system module (SRS) (4/9).
When the collision pulse is strong enough, an activation signal , a current pulse, to airbags front (8/30, 8/31, 8/32 and 8/61) and/or seatbelt tensioners (8/33, 8/34, 8/55, 8/56, and on certain models 8/92).
The front-end collision sensors (7/178 and 7/179) are also included in multi-point sensing in the control module. They register the collision pulse and send acceleration data to the control module. Airbags driver and passenger front are activated. Seatbelt tensioners front are activated.
The passenger airbag will not be activated if it is deactivated with the switch (3/157).
A collision signal is transmitted on a direct connection from the supplemental restraint system module (SRS) to the central electronic module (CEM)( 4/56) and phone module (PHM) (16/60) when the collision protection system is activated. These two control modules ensure that:
- the central locking system is unlocked
- the fuel pump (FP) is switched off
- windshield wipers are turned off if the vehicle is stationary
- interior lighting is activated
- warning lamps are lit
- the collision pulse is registered
- an automatic alarm is sent to CSC (customer service center) if the vehicle is equipped with Volvo On Call (Plus).

Front-end collision (only USA/CDN)




In case of a front-end collision a function is used that is called multi-point sensing. This means that the collision pulse is registered at several points. This function is integrated in the Supplemental restraint system module (SRS) (4/9). When the collision pulse becomes adequately high an activation signal, a current pulse, is sent to front airbags (8/30, 8/31, 8/32 and 8/61) and/or seat belt tensioners (8/33, 8/34, 8/55 and 8/56). The front impact sensors (7/178 and 7/179) are also included in the multi-point sensing in the control module. They register the collision pulse and send out acceleration data to the control module. Driver and front passenger airbags are activated. Seat belt tensioners front are activated. In case of a front-end collision where front airbags and front seat belt tensioners have deployed, the function for adaptive seat belt force limitation (see below) can also be activated. When the driver airbag is activated and the driver is wearing the seat belt, the control module sends an activation signal, a current pulse, to the adaptive steering column (8/99). The Occupant weight sensor (OWS) (7/93) is used to activate/deactivate the passenger airbag.
A collision signal is transmitted on a direct connection from the supplemental restraint system module (SRS) to the central electronic module (CEM)( 4/56) and phone module (PHM) (16/60) when the collision protection system is activated. These two control modules ensure that:
- the central locking system is unlocked
- the fuel pump (FP) is switched off
- windshield wipers are turned off if the vehicle is stationary
- interior lighting is activated
- warning lamps are lit
- the collision pulse is registered
- an automatic alarm is sent to CSC (customer service center) if the vehicle is equipped with Volvo On Call (Plus).

Function for adaptive seat belt force limitation (only USA/CDN)




In case of a front-end collision where the front airbags and the front seat belt tensioners (8/33 and 8/34) have deployed, the function for adaptive seat belt force limitation can also be activated. When the front airbag and the front seat belt tensioner are activated, the seat belt roller sensor (7/194, 7/195) starts to monitor the angle and the speed with which the seat belt is tensioned/tightened. The seat belt roller sensor sends information about the seat belt angle and speed to the Supplemental restraint system module (SRS) (4/9) in real time. The Supplemental restraint system module (SRS) also receives information from the seat position sensor (3/255, 3/256) about the position of the passenger or driver's seat. Then the control module can decide if the person in the vehicle is small or large. With this information the Supplemental restraint system module (SRS) decides if the seat belt force limiter shall be activated. If the adaptive seat belt force limiter (8/128, 8/129) is activated the Supplemental restraint system module (SRS) sends an activation signal, a current pulse, to the adaptive seat belt force limiter, which reduces the force from the seat belt on the chest.

Activating/deactivating the front passenger airbag (not USA/CDN)




If necessary, the front passenger airbag (8/31 and 8/32) can be deactivated. This is done using a switch (3/157) positioned on the dashboard on the passenger side.
When the switch position changes from "ON" to "OFF", the current levels change on the two Hall sensors which are connected to the switch.
The Hall sensors send, on directly connected cables, the changed current levels to Supplemental restraint system module (SRS) (4/9). The control module's software deactivates airbag passenger front, which means that the airbag remains inactive in case of a collision.
Supplemental restraint system module (SRS) also sends a signal on the CAN-net, to Central electronic module (CEM) (4/56), with a request to turn on warning light airbag passenger (PAD).
When the switch position changes from "OFF" to "ON", a new current level is sent from the Hall sensors to Supplemental restraint system module (SRS).
Then the control module's software activates the airbag, which means that the airbag has full function in case of a collision. At the same time the Supplemental restraint system module (SRS) sends a signal on the CAN-net, to Central electronic module (CEM) with a request to turn off warning light airbag passenger (PAD) and to turn on warning light activated airbag passenger (PAE).

Note! The activating switch, on/off, for the front passenger airbag and occupant weight sensor (OWS) must not be installed in the vehicle together.

Activating/deactivating front passenger airbag (only USA/CDN)




In normal conditions it is the information from the Occupant weight sensor (OWS) (7/93) that is the basis for if the Supplemental restraint system module (SRS) (4/9) shall activate or deactivate the front passenger airbag (8/31 and 8/32). Occupant weight sensor (OWS) communicates continuously with Supplemental restraint system module (SRS) on the local CAN-network. When a passenger is seated, with a weight exceeding a certain level, in the passenger seat the Occupant weight sensor (OWS) will inform the Supplemental restraint system module (SRS) about this. Then the control module's software activates the front passenger airbag, which means that the airbag has full function in case of a collision. At the same time, the Supplemental restraint system module (SRS) sends a signal on the CAN-network, to the central electronic module (CEM) (4/56), with a request that the warning light passenger airbag (PAD) shall be turned off. Then the Central electronic module (CEM) turns off the warning light for passenger airbag (PAD).
If the weight in the passenger seat front is under a certain level, then the Occupant weight sensor (OWS) will inform Supplemental restraint system module (SRS) about this. The control module's software then deactivates airbag passenger front, which means that the airbag remains inactive in case of a collision. At the same time the Supplemental restraint system module (SRS) sends a signal on the CAN-net, to Central electronic module (CEM), with a request to turn on warning light airbag passenger (PAD). Then Central electronic module (CEM) turns on warning light airbag passenger (PAD).

Note! The activating switch, on/off, for the front passenger airbag and occupant weight sensor (OWS) must not be installed in the vehicle together.

The occupant weight sensor (OWS) system (only USA/CDN)
The occupant weight sensor (OWS) is designed to meet the regulatory requirements of Federal Motor Vehicle Safety Standard (FMVSS) 208 and is designed to disable (will not inflate) the passenger's side front airbag under certain conditions.
The occupant weight sensor (OWS) works with sensors that are part of the front passenger's seat and safety belt. The sensors are designed to detect the presence of a properly seated occupant and determine if the passenger's side front airbag should be enabled (may inflate) or disabled (will not inflate).
The occupant weight sensor (OWS) will disable (will not inflate) the passenger's side front airbag when:
- the front passenger seat is unoccupied, or there are small/medium objects in the front passenger seat,
- the system determines that an infant is present in a rear-facing infant seat that is installed according to the manufacturer's instructions,
- the system determines that a small child is present in a forward-facing child restraint that is installed according to the manufacturer's instructions,
- the system determines that a small child is present in a booster seat,
- a front passenger takes his/her weight off of the seat for a period of time,
- a child or a small person occupies the front passenger seat.
The occupant weight sensor (OWS) uses a passenger airbag warning lamp (PAD) which will illuminate and stay lit to remind you that the passenger's side front airbag is disabled. The passenger airbag warning lamp (PAD) is located in the overhead console.

Note! The passenger airbag warning lamp (PAD) will illuminate for a short period of time when the ignition is turned on to confirm it is functional.

In cases when the airbag on the passenger side front (inflation possible) is activated, then warning light airbag passenger (PAD) will not be on.
The occupant weight sensor (OWS) is designed to disable (will not inflate) the passenger's side front airbag when a rear facing infant seat, a forward-facing child restraint, or a booster seat is detected. The passenger airbag warning lamp (PAD) will illuminate and stay lit to remind you that the passenger's side front airbag is disabled.

Note! Volvo recommends that children always be properly restrained in appropriate child restraints in the rear seats.

The occupant weight sensor (OWS) is designed to enable (may inflate) the passenger's side front airbag anytime the system senses that a person of adult size is sitting properly in the front passenger seat. The passenger airbag warning lamp (PAD) will be unlit and stay unlit.
The occupant weight sensor (OWS) detects pressure on the front passenger seat cushion as a result of load put in the seat. The occupant weight sensor (OWS) classifies the occupant as small or large based on whether the induced pressure is below or above a predetermined threshold. The threshold is defined between the pressure induced by children and the pressure induced by adults in accordance with the regulatory requirements of Federal Motor Vehicle Safety Standard (FMVSS) 208. If the occupant weight sensor (OWS) determines a small occupant classification, the passenger's side front airbag will be disabled and the passenger airbag warning lamp (PAD) will be lit. If the occupant weight sensor (OWS) determines a large occupant classification, the passenger's side front airbag will be enabled and the passenger airbag warning lamp (PAD) will be unlit.

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