The 960 and 940 after 1992 had SRS diagnostic capability using the On-Board Diagnostic (OBD) unit in the engine compartment. The 1987 to 1992 7 series, the 1990 to 1991 2 series and the 1992 940 also had a diagnostic capability. Click through to the Volvo Forum post to get the downloadable PDF.
Have a Volvo 940 or 960? Jump to the Volvo 940 and 960 SRS diagnostics. Same thing as this, but for those models.