Restraints - Design and Function (Xc): Diagnosis Volvo V70 II

Diagnostic services

The following diagnostic services are available for the SRS system

1. Read diagnostic trouble codes (DTCs)
2. Erase diagnostic trouble codes (DTCs) (all DTCs except those stemming from internal faults in the SRS unit can be erased)
3. The identity of the SRS system's SRS module and side impact sensors and all installed software can be read off via the VIDA station.

Diagnostic trouble codes (DTCs)

Diagnostic trouble codes (DTCs) are stored by the SRS module's internal diagnostic procedures. The diagnostic trouble codes (DTCs) are defined in the software which is installed in the factory. Diagnostic trouble codes (DTCs) are stored in the event of each diagnosis case automatically carried out by the SRS module or activated by the VIDA station.

Scheme 263

Airbag module

The air bag is inflated by a gaseous mixture consisting of Argon, Helium and oxygen. The gas cylinder is initiated by a pyrotechnic charge (12 g) which also contributes to the gas development. At ignition, the charge warms up the gaseous mixture which then expands to a greater volume, creating higher pressure.

Helium is only used to carry out leak tracing on the airbag during manufacture.

The passenger side airbag is standard for all markets except for the Nordic markets where it is an option.

The volume of a deployed airbag is approximately 150 liters.

Scheme 264

SIPS airbag

The SIPS airbag with electronic ignition is standard on both front seats. Bag volume is approximately 10 liters.

The airbag is inflated by a gas cartridge located inside the bag. The gas consists of a mixture of Argon (95%) and Helium (5%). (Helium is only used to be able to carry out leak tracing on the airbag during manufacture). The airbag also contains a pyrotechnic powder charge to heat, and thereby expand the gas mixture.

The SIPS airbag is triggered approximately 3 ms after impact. The bag reaches its operational pressure after 10 ms. Pressure in the bag begins to fall 25 ms after impact.

The SIPS bag volume has been increased in comparison to the previous version. This results in the rib cage being covered further forward and pressure is maintained for a longer period. This combination provides better protective qualities.

A new type of connector with a spring lock is used to connect the SIPS airbag to the SRS system. The connector is yellow.

The SRS system runs diagnostics on the SIPS bag up to the ignition wire.

Scheme 265

WHIPS seat

The aim of WHIPS (Whiplash Protection System) is to reduce the risk of whiplash injuries in the event of collision from the rear. The system is designed for maximum performance at low speed collisions. The majority of whiplash injuries occur during accidents at a speed of 10-20 km/h (6-12 mph).

WHIPS seats have a normal folding function, similar to the passenger seats in the present 850 series. However the mechanism has been modified to take a WHIPS deployment mechanism for the backrest in both joints (a pendulum function with a suppressing deformation element).

The mechanism consists of the following components

1. Mounting plate for seat backrest
2. Heat plate with window (23)
3. Link (25)
4. Deformation element (24)
5. Seat anchor plate (23)
6. Indicator pin (26)
7. Damper spring

WHIPS seats are standard for both front seats.

In relation to current seats, WHIPS seats backrests are more resistant to twisting because of the greater lower tube dimension while the upper section of the backrest is shaped like a closed beam. The springs for the backrest back pad are equipped with compression limiters (22)

In order to protect the occupants' heads during an accident, the head restraint is now in a more forward position (the same position as in the P90). The distance between the head restraint struts has also been reduced.

The deployment mechanism begins to operate in the event of a collision speed of approximately 14 to 18 km/h (9 - 11 mph), depending on the weight of the occupant (the collision speed at which the indicator pin shears off).

Scheme 266

In the event of a collision from the rear, the seat moves forward, thereby pressing the backrest against the occupant. The system then activates, going through two clearly defined phases.

Illustration A in (Scheme 266)

At activation the seat back moves first mainly backward in upright position, whereby the body is secured in a balanced way. The distance of this parallel movement is approximately 50 mm (1.97 in). At activation, the indicator pin (26) shears off.

Illustration B in (Scheme 266)

Instead of the occupant now being thrown forward, as in a traditional seat, the backrest now begins to angle backwards (up to 15 degrees). This is achieved using a deformation element (a link with set deformation qualities, 24) which collapses and therefore gently brakes movement (absorbs energy during the crash sequence). The compression limited springs distributes force evenly throughout the entire spine to avoid pressure points which often previously resulted in S-curvatures to the spine.

Because lesser collisions from the rear may also activate the system, a repair kit has bee produced. The WHIPS repair kit consists of

1. Deformation elements (x 2)
2. Indicator pins (x 2)
3. Return springs (x 2)
4. Link washer (x 2)
5. Pivot bushing (x 2)
6. Pivot shaft with nut (x 2)
7. Notched washer

SRS diagnostic functions

See Diagnostic functions

See Diagnostic functions