Signal Missing

Signal missing

Checking communication




- Ignition on.
Check whether communications with the siren control module (SCM) are working by reading out the control module part number.





Can the part number be read off?

Yes - DONE

No - Checking the power supply and ground terminal

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Checking the power supply and ground terminal




- Ignition off.

Hint: For information about cables and connectors, see the wiring diagram for the relevant car model.

Check the cable between central electronic module (CEM) terminal #E36 (#36) and siren control module (SCM) terminal #A3. Check for an open-circuit.
Check the signal cable between central electronic module (CEM) terminals #G1 (#1) and siren control module (SCM) terminal #A2. Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
Check the cable between siren control module (SCM) terminal #A1 and ground. Check for an open-circuit. Also check the ground terminal for oxidation.
Remedy the cables as necessary.

Other information
- Connecting the breakout box Connecting The Breakout Box, Central Electronic Module (CEM)
- Anti-theft protection siren Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals

Was a fault detected?

Yes - Verification

No - Replacing the control module

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Replacing the control module




- Ignition off.
If no fault is discovered in the cables for the siren control module (SCM), the unit will probably need to be replaced.

Other information
- Anti-theft protection siren Service and Repair

Select Continue.

Continue - Verification

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Fault-tracing information

FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking the power supply and ground terminal

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Verification




Verification

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








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on.
Check that it is possible to activate the starter motor.
Check that it is possible to remove the key from the ignition switch.
If the vehicle has GDL lamps, also check the following:
- Activate low beam
- Activate high beam flash
- Activate high beam.
Check that the functions are OK.

Are the functions OK?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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