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)
• side impact sensors (7/115, 7/116, 7/208 and 7/209)
• door mounted inflatable curtains (8/66 and 8/67)
• SIPS bags (8/51 and 8/52)
• frontal impact sensor (7/178 and 7/179)
• front seat belt buckles (3/93 and 3/94)
• adaptive steering column (8/99) (USA/CDN only)
• seat position sensors (3/255 and 3/256) (USA/CDN only)
• adaptive seatbelt force limiter (8/128 and 8/129) (USA/CDN only)
• switch on/off, front passenger airbag (3/157) (not USA/CDN)
• occupant weight sensor (OWS) (7/93) (USA/CDN only)
• roll-over bar cassette (8/57 and 8/58).

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 red warning lamp 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 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 red general warning lamp lights up if the SRS indicator lamp stops working. If the CAN communication between the supplemental restraint system (SRS) module and the driver information module (DIM) fails, the SRS 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.