Nissan Maxima Service and Repair Manual: P1612 chain of ECM-IMMU
BCM performs the ID verification with ECM that allows the engine to start. Start the engine if the ID is OK.
ECM prevents the engine from starting if the ID is not registered. BCM starts the communication with ECM if ignition switch is turned ON.
DTC DETECTION LOGIC
If DTC P1612 is displayed with DTC U1000, first perform the trouble diagnosis for DTC U1000. Refer to SEC-29, "DTC Logic".
If DTC P1612 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010. Refer to SEC-30, "DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PERFORM DTC CONFIRMATION PROCEDURE
Turn ignition switch ON under the following conditions:
CVT selector lever is in the P or N position.
Do not depress brake pedal.
Check "Self Diagnostic Result" with CONSULT.
Replace BCM. Refer to BCS-79, "Removal and Installation".
Perform initialization with CONSULT.
For initialization, refer to CONSULT Immobilizer mode and follow the on-screen instructions.