Faulty Signal. Permanent Fault
Faulty signal. Permanent fault
Checking component
Caution! SRS-311 is stored if a fault occurs in the left front seat belt tensioner or the left rear seat belt tensioner. It may be necessary to carry out fault-tracing on the front and rear seat belt tensioners to find the fault.
- Make a note of the anti-theft radio code.
- Ignition off.
- Disconnect the battery negative lead.
- Disconnect the connector from the left seat belt tensioner, front or rear.
Warning! Under no circumstances use an ohmmeter or other live measuring instrument to take readings on a disconnected non-deployed pyrotechnical seat belt tensioner. This could deploy the seat belt tensioner!
- Install special tool 998 8695 TEST DEVICE 998 8695 Test Device onto the left seat belt tensioner connector, front or rear.
Caution! The special tool must be checked and faultless. If the tool is defective it will cause errors in the diagnosis and make fault-tracing harder.
- Ignition on.
- Connect the battery negative lead.
- Read off diagnostic trouble codes (DTCs).
If the fault is in the left seat belt tensioner (front or rear)the diagnostic trouble code (DTC) status should have switched to intermittent fault. Try replacing the seat belt tensioner and carrying out a verification.
Other information:
- To access / replace the seat belt tensioner, see Seat belt Service and Repair.
Does the diagnostic trouble code (DTC) status change?
Yes - Verification
No - Checking components and wiring
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Checking components and wiring
- Ignition off.
- Disconnect the control module connector.
- Check the control module terminal pins visually.
- Check that the plastic pins are undamaged. Their function is to separate the short-circuit element from the terminal pins when the control module is connected.
- Remove special tool 998 8695 TEST DEVICE 998 8695 Test Device.
- Connect the control module connector.
- Ignition on.
Note! Diagnostic trouble code (DTC) SRS-312 is stored after this reading has been taken. Ignore the diagnostic trouble code (DTC), which is stored due to this operation.
Connect oscilloscope between seat belt tensioner #1 and ground.
The oscilloscope should now display a spiked pulse with an interval of approximately 500 ms.
If the value deviates there is a short-circuit in the cable. Replace the cable harness.
Remedy as necessary.
Other information:
- To access / replace the control module, see SRS control module Service and Repair.
Is the value correct?
Yes - Verification
No - No Fault Found Fault-tracing information
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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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