Faulty Signal. Permanent Fault
Faulty signal. Permanent fault
Checking components
- Make a note of the anti-theft radio code
- Ignition off
- Disconnect the battery negative lead
- Disconnect the connector from the driver's airbag.
Warning! Under no circumstances use an ohmmeter or other live measuring instrument to take readings on a disconnected, non-deployed steering wheel module. This could deploy the airbag.
- Install special tool 998 8695 TEST DEVICE 998 8695 Test Device on the connector for the airbag.
Caution! The special tool must be checked and fault-free. If the tool is defective it will cause errors in the diagnosis and make fault-tracing harder.
Hint: Check that the connectors between the control module and driver's airbag are connected. Because the short-circuit element in the connector can short-circuit the signal when the connector is not connected, which in turn causes this fault
- Ignition on
- Connect the battery negative lead.
- Read off diagnostic trouble codes (DTCs).
If the fault is in the airbag, the status of the diagnostic trouble code (DTC) will have switched to an intermittent fault. Try replacing the driver's airbag and then carrying out a new verification.
Other information:
- To access or replace the driver's airbag, see Airbag steering wheel module, steering wheel and contact reel Airbag Steering Wheel Module, Steering Wheel and Contact Reel Replacement.
Does the diagnostic trouble code (DTC) status change?
Yes - Verification
No - Checking the cable and the control module
-------------------------------------------------
Checking the cable and the control module
- Ignition off
- Remove the contact reel
- Ignition on.
Connect an oscilloscope between contact reel terminal #1 and ground. The oscilloscope should now display a spiked pulse with an interval of approximately 500 ms.
If the value is normal, the fault is in the contact reel. Replace the contact reel.
If the value deviates there is a short-circuit in the cable. Replace the cable harness.
Check the control module terminal pins visually.
Check that the plastic pins are not damaged. Their function is to separate the short-circuiting element from the terminal pins when the control module is connected.
The control module must be replaced if the plastic pins are damaged.
Remedy as necessary.
Other information:
- To access or replace the contact reel, see Airbag steering wheel module, steering wheel and contact reel Airbag Steering Wheel Module, Steering Wheel and Contact Reel Replacement
- To access and replace the control module see SRS control module Service and Repair.
Select Continue when the fault has been remedied.
Continue - Verification
-------------------------------------------------
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
------------------------
VERIFIED - FAULT FOUND
VERIFICATION FAILED - Fault-tracing information
-------------------------------------------------
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
------------------------
Attempt New Test - Checking components
-------------------------------------------------