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Home >> Volvo >> 1999 >> C70 L5-2.4L Turbo VIN 56 B5254T >> Repair and Diagnosis >> Restraints and Safety Systems >> Air Bag Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Checking Communication With SRS Control Module >> Checking Communication With The SRS Control Module

Checking Communication With The SRS Control Module






Checking communication with the supplemental restraint system module (SRS)

Checking communication with the SRS system




- Ignition on





Is there communication with the SRS system?

Yes - Checking the cable

No - Checking the power supply

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Checking the cable












- Ignition off.
- Disconnect VCT 2000 from the data link connector (DLC).
- Disconnect the battery negative lead.
- Disconnect the control module.
Check the cable between control module terminal #9 and data link connector (DLC) terminal #7. Check for an open-circuit. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Connect an ohmmeter between the battery positive terminal and data link connector (DLC) terminal #7. Take readings. Check for short-circuit to supply voltage Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check the connectors. Check for contact resistance and oxidation Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.

Other information
- Voltage at control module connector terminal #9 must be approximately 10 V.









Select Continue once the fault has been remedied.

Continue - Checking voltage to the control module

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Checking voltage to the control module




- Ignition on
Take readings using a voltmeter between control module connector terminal #5 and ground.





The voltmeter must display battery voltage.

OK - Replacing the component

Not OK - SRS-129
Fault-trace. See Signal too low. Permanent fault Signal Too Low. Permanent Fault.

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Replacing the component
Try replacing the control module.

Select Continue once the fault has been remedied.

Continue - Verification

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Checking the power supply








- Disconnect VCT 2000 from the data link connector (DLC).
- Ignition on
Connect a voltmeter between the data link connector terminal #16 and ground









The voltmeter must display battery voltage.

OK - Checking the function

Not OK - Checking for open-circuit

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Checking for open-circuit
Check fuse number 7 in the central electrical unit.
Check the cable between data link connector (DLC) terminal #7 and fuse number 7 in the central electrical unit. Check for an open-circuit. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Check main fuse number 5 in the central electrical unit.
Check the cable between main fuse number 5 and fuse number 7 in the central electrical unit. Check for an open-circuit. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Also check the connectors. Check for contact resistance and oxidation. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.













Continue - Checking the power ground and signal ground

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Checking the power ground and signal ground
Check the cable between data link connector (DLC) terminal #4 and ground and between terminal #5 and ground. Check for an open-circuit. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.









Select Continue once the fault has been remedied.

Continue - Checking the function

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Checking the function








- Ignition off.
- Reinstall the components, reconnect the connectors etc.
- Connect VCT 2000 to the data link connector (DLC).
- Ignition on
Try establishing communication with the supplemental restraint system module (SRS).





Is there communication now?

Yes - FAULT FOUND

No - Checking Volvo System Tester

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Checking Volvo System Tester
Check Volvo System Tester, voltage supply and ground to the data link connector (DLC).

Select Continue once the fault has been remedied.

Continue - DONE

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Verification




Verification

Hint: After repairs have been completed they must be verified as follows to ensure that the fault has been eliminated:








- Ignition off.
- Reinstall components, reconnect connectors etc.
- Ignition on.
Try to establish communication with the SRS system.





Has contact been established?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should be diagnosed and remedied. Since this is not the case the fault-tracing process has failed.
Complete the fault-tracing for those fault or try again.

Do you want to terminate fault-tracing at this time?

Yes - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Checking communication with the SRS system

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SRS-129





Signal too low. Permanent fault

Checking component

Hint: The battery should be checked for loose terminal connections or low battery voltage before starting fault-tracing.

Remedy as necessary.


Continue - Checking connector

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Checking connector












- Make a note of anti-theft radio code.
- Ignition off.
- Disconnect battery negative lead.
- Disconnect control module and ignition switch connectors.
Remedy ignition switch and control module connector for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check for damage etc.
Check cable between battery and ignition switch and cable between ignition switch and control module #5 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault and a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.










Select Continue when the fault has been remedied.

Continue - Checking generator (GEN)

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Checking generator (GEN)








- Connect battery negative lead.
- Start the engine.
Connect a voltmeter between generator (GEN) D+ terminal and ground to check generator function.
When the engine is running, voltage should be approximately 13-15 V.
When engine is off and ignition is on, voltage should be approximately 0.7 V.
The generator must be repaired or replaced if the value is not correct.
Remedy as necessary.









Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.




- Ignition off
- Disconnect the battery negative lead
- Reinstall the connectors, components etc.
- Ignition on
- Connect the battery negative lead.

Warning! There must not be anyone inside the passenger compartment when the battery is connected.

- Read off diagnostic trouble codes (DTCs).
The fault is no longer present if the status of the diagnostic trouble code (DTC) has changed to intermittent.





Does the status change?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Checking component

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - No Fault Found

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