LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Infiniti >> 2012 >> G37 Base, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different car >> Section 111 (EV Control System) >> DTC/Circuit Diagnosis >> DTC P31DB: System Main Relay + >> Diagnosis Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis Procedure

WARNING: This page is about a different car, the 2011 Nissan Leaf. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK HARNESS
    1. Turn power switch OFF.
    2. Disconnect VCM harness connector and Li-ion battery harness connector.
    3. Check continuity between VCM harness connector and Li-ion battery harness connector.
      CONTINUITY REFERENCE CHART

      + - Continuity
      VCM Li-ion battery
      Connector terminal Connector terminal
      E63 107 B24 17 Existed
    4. Check continuity between Li-ion battery harness connector and ground
    CONTINUITY REFERENCE CHART

    + - Continuity
    Li-ion battery
    Connector terminal
    B24 17 Ground Not existed

    Is the inspection result normal? 

    YES: Go to 2.

    NO: Repair harness or connector.

  2. CHECK SYSTEM MAIN RLY CIRCUIT
    1. Check continuity between Li-ion battery connector terminals.
      CONTINUITY REFERENCE CHART

      Li-ion battery Continuity
      Terminals
      16 17 Existed
    2. Check continuity between Li-ion battery connector terminal and ground.
    CONTINUITY REFERENCE CHART

    + - Continuity
    Li-ion battery
    Terminals
    17 Ground Not existed

    Is the inspection result normal? 

    YES: Check intermittent incident. Refer to "INTERMITTENT INCIDENT ".

    NO: Repair or replace error-detected parts.