Here is the guide on how to solve Scania truck ALM alarm system trouble codes ALM 310 311 siren short circuit error.
Preparations:
Scania SDP3 2.61.2 Truck Diagnostic Software
Siren, short circuit
Error identification
Siren N9 is short-circuited to ground/the voltage supply..
Cause
Fault in harness-to-component connectors or cable harness for siren N9.
Fault in siren N9.
Faulty ALM control unit E7.
Symptom
The siren does not work correctly.
Action
Disconnect siren N9.
Measure against ground and voltage on the pins in the nearest harness-to-component connector leading to control unit pin A11.
Disconnect the harness-to-component connector on the control unit.
Measure for short circuits throughout the cable harness.
If there are several harness-to-component connectors between the component and the control unit, also measure these to locate the fault.
If the fault is not in the cable harness or the component, it is probably an internal fault in the control unit.
