Symptom Related Diagnostic Procedures

Fault symptoms




The SRS warning lamp is lit but no DTC is stored. (Normally the SRS warning lamp lights when the ignition is switched to position II and goes out after 10 seconds or when the engine starts.)

Cause of faults:
- Battery voltage too low (<9 V) or battery voltage too high (>18.5 V).
- D+ voltage too low.

^ Start fault tracing by checking communication with the SRS system.

Checking Communication With The SRS System




- Ignition off.

NOTE: Before connecting the Volvo Scan Tool (ST) check that the correct memory cassette is being used.




- Connect the Volvo Scan Tool (ST) to the data link connector (DLC).




- Ignition on.




- Power up the Volvo Scan Tool (ST) with the switch on the adapter box. The adapter box, which is pan of the Volvo Scan Tool (ST) kit, may sometimes be called the switch or just the adapter.
- Check communication with the SRS system. Displaying & Reading Trouble Codes

If communication with the SRS system is OK:
The fault is probably in the D+ supply to the SRS sensor module.
- Continue with checking D+ supply from generator.

If there is no communication with the SRS system:
The fault is probably in the battery voltage X-supply to the SRS sensor module.
- Go to: Communication Problems With the Volvo Scan Tool

Checking D+ Supply From Generator




- Ignition off.




- Remove connector (1-pin receptacle terminal) from generator D+ connecting pin.








- Ignition key in position II.
- Connect a voltmeter between ground and generator D+ connecting pin.
The voltmeter should read between 0.7 V and approx. 2 V.







- Start engine.
- Connect a voltmeter between ground and generator D+ connecting pin.
The voltmeter should read approx. 14.5 V.

If both readings are OK:
D+ supply from the generator is OK. There is probably an open-circuit in the cable between the generator and the SRS sensor module.
- Continue with checking D+ supply to the SRS sensor module.

If any reading is abnormal:
The fault is in the generator.
^ Replace the generator.

Checking D+ Supply To The SRS Sensor Module




- Ignition off.




- Disconnect battery negative lead.




- Connect connector (1-pin receptacle terminal) to generator D+ connecting pin.




- Expose and remove SRS sensor module connector.





CAUTION: Never touch the sensor module pins. There is a risk of static discharge which could damage the sensor module.












- Ignition key in position II.
- Connect a voltmeter between ground and sensor module connector terminal 12.
The voltmeter should read between 0.7 V and approx. 2 V.












- Start engine.
- Connect a voltmeter between ground and sensor module connector terminal 12.
The voltmeter should read approx. 14.5 V.

If both readings are OK:
There is no open-circuit in the cable between the generator and the SRS sensor module connector terminal 12.
^ Replace sensor module.

If any reading is abnormal:
If the voltmeter reads 0 V there is an open-circuit in the cable.
^ Check the cable between the sensor module connector terminal 12 and generator connector D+ for an open-circuit. Checking Cabling and Connections