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:
- driver's airbag stages 1 and 2 (8/30 and 8/61)
- driver's airbag stage 3 (8/123) (XC90 USA/CDN only)
- passenger airbag stages 1 and 2 (8/31 and 8/32)
- passenger airbag stage 3 (8/124) (XC90 USA/CDN only)
- seat belt tensioners front and rear (8/33, 8/34 8/55, 8/56 and 8/62)
- seat belt tensioners third row (8/94 and 8/95) (XC90 7 seater only)
- side impact sensors (7/108, 7/109, 7/115 and 7/116)
- left and right inflatable curtains (8/66 and 8/67)
- left and right rear inflatable curtains (8/96 and 8/97) (XC90 7 seater only)
- SIPS bags (8/51 and 8/52)
- front impact sensors (7/178 and 7/179) (certain markets and models only)
- front seat belt buckles (3/93 and 3/94)
- adaptive steering column (8/99) (XC90 USA/CDN only)
- switch on/off, front passenger airbag (3/157) (not USA/CDN)
- occupant weight sensor (OWS) (7/93) (certain markets and models only)
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 indicator lamp. The SRS indicator 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 indicator 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 warning lamp lights and a warning text is displayed in the driver information module (DIM).
The driver information module (DIM) continuously transmits a signal to the supplemental restraint system module (SRS) via the controller area network (CAN) with information about whether the SRS indicator lamp is working or not. The general warning lamp will light and a text message will be displayed in the driver information module (DIM) if the SRS warning lamp is not working. If the CAN communication between the supplemental restraint system (SRS) module and the driver information module (DIM) fails, the red lamp in the general warning lamp lights up and text is displayed in the driver information module (DIM). If the faults disappear and the driver information module (DIM) can transmit information to the supplemental restraint system module (SRS) and the status of the SRS warning lamp is OK, the warning lamps will return to normal function.