Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information

IMM-321 Communication link to the engine control module (ECM)

Condition




In the first two seconds after ignition, the immobilizer control module checks the communication link between the immobilizer control module and the engine control module (ECM) for an open-circuit and short-circuit to supply voltage. Diagnostic trouble code (DTC) IMM-321 is stored if the immobilizer control module cannot communicate with the engine control module (ECM) and there is no short-circuit to ground.
Diagnostic trouble code (DTC) IMM-321 is stored in cars with engine control module (ECM) Fenix 5.2 if any of the following safety functions are activated:
- Ignition off when vehicle speed is higher than 30 km/h (18.6 mph) and the restart occurs within four minutes.
- The engine stops with the ignition on and restart occurs without the ignition key being twisted back to position 0 or I and engine starts again, within four minutes from when it stopped.
The safety functions can be activated by normal driver actions and diagnostic trouble code (DTC) IMM-321 can be stored without there being anything wrong with the car.
If there is no power supply (+15 and/or +30) to the engine control module (ECM) it indirectly causes diagnostic trouble code (DTC) IMM-321 to be stored because there cannot be any communication between the immobilizer control module and the engine control module (ECM).
The diagnostic trouble code (DTC) is erased when the counter value is one.

Possible source
- The cable between the engine control module (ECM) and immobilizer control module #2 (Fenix 5.2) or #4 (Denso, ME7, MSA15.7, MSA15.8) is short-circuited to supply voltage during start.
- Open-circuit in cable between engine control module (ECM) and immobilizer control module #2 (Fenix 5.2) or #4 ((Denso, ME7, MSA15.7, MSA15.8) during start.
- Contact resistance in cable terminals between immobilizer control module #2 (Fenix 5.2) or #4 (Denso, ME7, MSA15.7, MSA15.8) and engine control module (ECM).
- Intermittent open-circuit while driving on power supply to immobilizer control module #5, loose connections in supply +15 for example.
- Intermittent open-circuit while driving on power supply to immobilizer control module #6, loose connections in supply +30 for example.
- Intermittent open-circuit in ground terminal to immobilizer control module #8 while driving.
- Ignition operation with engine control module (ECM) disconnected.
- Fault in engine control module (ECM).
- Wrong engine control module (ECM) installed.
- Open-circuit in power supply to engine control module (ECM).

Fault symptom[s]
- Engine starts but stops immediately.