Diagnostic trouble code (DTC) information

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

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

Condition

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

Courtesy of VOLVO CARS OF NORTH AMERICA.

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 detect a communication 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 the car is moving faster than 30 kph 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 engine control module (ECM)

The diagnostic trouble code (DTC) is erased when the counter value is one.

Possible Source

The cable between engine control module (ECM) and control module immobilizer #2 (Fenix 5.2) or #4 (M4.4, MSA15.7) is short-circuit to supply voltage during the start.
Open-circuit in cable between engine control module (ECM) and immobilizer control module #2 (Fenix 5.2) or #4 (M4.4, MSA15.7) during the start.
Contact resistance in cable terminals between control module immobilizer #2 (Fenix 5.2) and #4 (M4.4, MSA15.7) 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]

The engine starts but stalls directly.