Signal Faulty. Permanent Fault
Signal faulty. Permanent fault
Checking the components
- Make a note of any radio code.
- Ignition off.
- Disconnect the battery negative lead.
- Disconnect connector from passenger airbag.
Warning! Never use an ohmmeter or any other charged measuring instrument on a disconnected, undeployed air bag module. There is a risk that the air bag could be deployed!
- Insert the special tool 998 8695 TEST DEVICE 998 8695 Test Device in the air bag connector.
Caution! The special tool must be checked and fault-free. If the tool is faulty, this will cause an incorrect display in the diagnosis and make fault localization harder.
- Ignition on.
- Connect the battery negative lead.
- Read the diagnostic trouble codes.
If a fault is found in the passenger airbag the status will now have changed to intermittent fault; test by replacing the passenger airbag and verify afterwards.
Additional information:
- To access/replace passenger airbag, see Passenger airbag module Passenger Airbag Module.
Has the status of the diagnostic trouble code changed?
Yes - Verification
No - Checking leads and control unit
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Checking leads and control unit
- Ignition off.
- Disconnect control unit connector.
- Visually check contact pin on control unit.
- Check that the plastic pin is intact. Its function is to isolate the short-circuit plate from the pin when the control unit is connected.
- If the plastic pin is broken, the control unit must be replaced as described in.
- Disconnect the special tool 998 8695 TEST DEVICE 998 8695 Test Device.
- Connect control unit connector.
- Ignition on.
Connect an oscilloscope between passenger air bag 1 and earth.
The oscilloscope should now show a spiked pulse with a period time of approx. 500 ms.
If the value deviates from this, this indicates that the wire is short circuited; replace the cable harness.
Note! After this test, diagnostic trouble code SRS-222 is displayed. Ignore this code, which is displayed as a result of the test.
Additional information:
- To access/replace passenger airbag, see Passenger airbag module Passenger Airbag Module.
- To access/replace control unit, see Service and Repair.
Does the value deviate from this?
Yes - Verification
No - Trouble-shooting 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 - Trouble-shooting information
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Trouble-shooting 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 the components
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