Side Impact Sensor
The side impact sensors in the car are used to measure and evaluate the collision pulses. An assessment is then transmitted to the supplemental restraint system (SRS) module.
The sensors used in the car are
- Two side impact sensors in the B-post
- Two side impact sensors in the C-post.
The side impact sensors have integrated logic which, in the event of a collision, determines whether the impact was sufficient to warrant transmitting a trigger pulse to the control module to deploy the side impact airbag. Only the side impact protection on the side from which the signal was sent can be deployed.
The side impact sensors transmit continuous OK signals to the control module to indicate that they are working. In the event of a fault in the side impact sensor, a fault signal is transmitted to the control module which then stores a diagnostic trouble code (DTC). A diagnostic trouble code (DTC) is also stored when the control module has not received an OK signal. Each side impact sensor has a software ID. The ID is used to check that the correct side impact sensor is installed. This is because the activation level of the signal which is transmitted to the control module is not necessarily the same for the different side impact sensors.
The front (B-post) and rear (C-post) side impact sensors are a different color and have different coding on their connectors to simplify installation. The front side impact sensors cannot be installed in place of the rear sensors and vice versa.
Data transmission occurs on the same cable used for power supply, i.e. one cable to each side impact sensor.
Driver Airbag
Scheme 398
Front Passenger Airbag
The airbags at the front of the car are
- Driver's airbag - 2 stage deployment (introduced model year 2001)
- Driver's airbag - 1 stage deployment (S80 1999-2000 model year only)
- Front passenger airbag - 2 stage deployment (introduced model year 2001)
- Front passenger airbag - 1 stage deployment (S80 1999-2000 model year only).
1 Stage Deployment (Model Year 1999-2000)
The driver's airbag contains a pyrotechnical charge and an igniter. In the event of activation the charge combusts and the gas which develops is blown into the airbag.
2 Stage Deployment (Model Year 2001-)
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. That is one output 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 activation 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 activation 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.
The driver's airbag is located in the steering wheel. The passenger airbag is located above the glove compartment in the dashboard.
Note. Never use an ohmmeter or similar tool to test airbags or seat belt tensioners. Disconnect airbags or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.