3360168 - A20 ALARM SIREN NOT WORKING

When the alarm is activated, the system goes on/off correctly (visual signals and deterrent led activation working) but siren does not go off. Furthermore, with the alarm on, an intrusion attempt is indicated only by the flashing of the turn signals, without an accompanying acoustic signal from the siren.
The alarm system is managed by the body computer node, which controls the acoustic signal siren.
Results of the tests
0CHECKING WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Connect the diagnostic equipment to the body computer node and check that the alarm system configuration has been correctly programmed while in parameter mode.Continue to Step 1Alarm siren control unit absent.Check car compliance.
1CHECKING WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Keep the Examiner connected and check for errors in the antitheft siren control unit.Continue to Step 2Error found: siren anomaly Check that the connector on the antitheft siren control unit is correctly connected.
A-Bus serial line with open circuit. Restore A-Bus serial line continuity/insulation See   E7015  ALARM
2CHECKING WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Keep the Examiner connected and carry out active diagnosis on the antitheft siren control unit.Continue to Step 3Antitheft siren control unit not working.Change the antitheft siren control unit ( Op. 5580E46)
3CHECKING CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persistsChange the body computer node ( Op. 5505A32)Search for the fault starting from another symptom'