Checking The SRS System
When the ignition is switched to position II or III, CAN communication is checked, there is a status check of the internal supplemental restraint system (SRS) functions (4/9) and a status check of all directly connected components, such as:
- driver airbag (8/123)
- passenger airbag (8/124)
- belt tensioners (8/33, 8/34, 8/55 8/56 and 8/62)
- belt tensioner, waist (8/92) (certain markets only)
- side impact sensors (7/108, 7/109, 7/115 and 7/116)
- side impact sensor (pressure sensor) (7/208 and 7/209) (only XC60 or USA/CDN)
- inflatable curtains (8/66 and 8/67)
- SIPS bags (8/51 and 8/52)
- front impact sensor (7/178 and 7/179) (not XC60)
- front seat belt buckles (3/93 and 3/94)
- rear belt buckles (3/217, 3/218 and 3/219) (certain markets only)
- adaptive steering column (8/99) (only USA/CDN)
- seat position sensor (3/255 and 3/256) (only USA/CDN)
- adaptive seatbelt force limiter (8/128 and 8/129) (only XC60 or USA/CDN)
- seatbelt retractor sensor (7/194 and 7/195) (only XC60 or USA/CDN)
- switch airbag passenger front (3/157) (not USA/CDN)
- occupant weight sensor (OWS) (7/93) (only USA/CDN)
In addition to these directly connected components, communication with Closing Velocity Module (CVM) (4/125) (only XC60) is also checked.
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 warning lamp remains lit and a warning text is displayed in the driver information module (DIM)
- the general red warning lamp lights and a warning text is displayed in the driver information module (DIM)
- information light is lit and any text message is shown on the Driver information module (DIM) (2008-).
The driver information module (DIM) continuously sends a signal via the CAN 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 SRS 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.