LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Infiniti >> 2003 >> Q45 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Computerized Engine Controls >> Engine Control Module (ECM) >> Power & Ground Circuits (G35)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Power & Ground Circuits (G35)

  1. Attempt to start engine. If engines does not run, go to next step. If engine runs, go to step  7.
  2. Turn ignition switch to OFF position. Then turn ignition switch to ON position. Check voltage between ECM terminal No. 43 and ground. See Figure. Battery voltage should exist. If voltage is as specified, go to step  4. If voltage is not as specified, go to next step.
  3. Check the following:
    • Harness connectors M72 and F102.
    • Fuse block (J/B) connector M4.
    • 10-amp fuse.
    • Harness for open or short between ECM and fuse.

    Repair as necessary.

  4. Turn ignition switch to OFF position. Disconnect ECM harness connector. Check harness continuity between ECM terminals No. 48, 57, 106, 108 and engine ground. See Figure. Continuity should exist. Also check harness for short to power. If results are not as specified, go to next step. If results are as specified, go to step  6.
  5. Check the following:
    • Joint connector-4.
    • Harness for open or short between ECM and engine ground.

    Repair as necessary.

  6. Reconnect ECM harness connector. Turn ignition switch to ON position. Check voltage between ECM terminals No. 31 and ground. See Figure. Battery voltage will exist. If voltage is as specified, see IGNITION COIL & Power Transistor (G35)  in IGNITION SIGNAL under IGNITION SYSTEM. If voltage is not as specified, go to next step.
  7. Turn ignition switch to OFF position and then ON. Check voltage between ECM terminals No. 110, 112 and ground. See Figure. When ignition switch is turned to OFF position, battery voltage should exist for a few seconds and then drop to zero volts. If voltage is as specified, go to next step. If battery voltage does not exist, go to step  10. If battery voltage remains for more than a few seconds, go to step  17.
  8. Disconnect ECM and IPDM E/R harness connectors. Check for continuity between ECM harness connector terminal No. 31 and IPDM E/R harness connector terminal No. 35. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Continuity should exist. If results are not as specified, go to next step. If results are as specified, go to step  17.
  9. Check the following:
    • Harness connectors E12 and F3.
    • Harness for open or short between ECM and IPDM E/R.

    Repair as necessary.

  10. Turn ignition switch to OFF position. Check voltage between ECM terminal No. 38 and ground. See Figure. Battery voltage should exist. If voltage is as specified, go to next step. If voltage is not as specified, go to step  13.
  11. Disconnect ECM and IPDM E/R harness connectors. Check for continuity between ECM harness connector terminals No. 110, 112 and IPDM E/R harness connector terminal No. 33. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL, Continuity should exist. If continuity is not as specified, go to next step. If continuity is as specified, go to step  16.
  12. Check the following:
    • Joint connector-3.
    • Harness connectors E12 and F3.
    • Harness for open or short between ECM and IPDM E/P.

    Repair as necessary.

  13. Disconnect ECM and IPDM E/R harness connectors. Check for continuity between ECM harness connector terminal No. 38 and IPDM E/R harness connector terminal No. 44. Continuity should exist. If results are not as specified, go to next step. If results are as specified, go to step  15.
  14. Check the following:
    • Harness connectors E11 and F2.
    • Harness for open or short between ECM and IPDM E/P.

    Repair as necessary.

  15. Disconnect 15-amp fuse from IPDM E/R. Inspect fuse. If fuse is okay, go to step  17. If fuse is faulty, replace 15-amp fuse.
  16. Turn ignition switch to OFF position. Disconnect ECM harness connector. Check harness continuity between ECM harness connector terminals No. 48, 57, 106, 108 and engine ground. See Figure. Continuity should exist. Also check harness for short to power. If results are not as specified, repair harness as necessary. If results are as specified, go to next step.
  17. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If results are as specified, inspection is complete.
scientia non olet · About LEMON Manuals