Diagnostic trouble code (DTC) information

IMM-312 Communication with engine control module (ECM) 

Condition 

Fig 1: Immobilizer Control Module And Engine Control Module (ECM) Communication Diagram

Courtesy of VOLVO CARS OF NORTH AMERICA.

The diagnostic trouble code (DTC) applies only to cars with the EMS 2000 and Melco 1 engine management systems.

In the two seconds after the ignition is switched on the immobilizer control module checks for too low a signal in the communication link between the immobilizer and engine control module. Diagnostic trouble code (DTC) IMM-312 is stored if a fault is detected.

Possible Source 

• Short-circuit to ground in the communication link between immobilizer control module #4 and engine control module (ECM) when the engine is started.

Fault symptom[s] 

• The indicator lamp in the combined instrument panel is lit.
• The engine starts but stops immediately.