2000 Infiniti QX4FACTORY OEM SERVICE PROCEDURE

Power & Ground Circuits (Maxima)

  1. Start engine. If engine starts, go to step  5. If engine does not start, turn ignition off and on. Measure voltage between ground and PCM harness connector terminal No. 43 (Red wire) by backprobing. See Fig 1 and Fig 3 . If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
    Fig 1: Locating PCM & PCM Harness Connector (Maxima)
    G00015111Courtesy of NISSAN MOTOR CO., U.S.A.
  2. Turn ignition off. Disconnect PCM harness connector. Check continuity between ground and PCM harness connector terminals No. 48, 57, 106 and 108 (Black wires). See Fig 3. If continuity exists, go to next step. If continuity does not exist, repair open or short in ground circuit(s).
  3. Remove ECCS relay. See Fig 2. Check voltage between ground and fuse block relay cavities No. 2 and 6. If voltage exists, go to next step. If voltage does not exist, check 15-amp fuses and harness between relay and battery.
    Fig 2: Locating ECCS Relay (Maxima)
    G99A51110Courtesy of NISSAN MOTOR CO., U.S.A.
  4. With PCM harness and ECCS relay disconnected, measure continuity of White/Black wire between ECCS relay harness connector terminal No. 1 and PCM harness connector terminal No. 26. See Fig 3 and Figure . If continuity exists, circuit is operating properly, check ignition signal. See DTC P1320: IGNITION SIGNAL in SELF-DIAGNOSTICS - MAXIMA article. If continuity does not exist, repair open in White/Black wire.
  5. Turn ignition on with engine off. Measure voltage between ground and PCM harness connector terminal No. 67 (White/Blue wire) by backprobing. See Fig 3. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  6. While turning ignition on and off, measure voltage between ground and PCM harness connector terminals No. 110 and 112 (Red/Green wires) by backprobing. Battery voltage should exist for a few seconds after turning ignition off. If voltage is as specified, go to step  10. If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds, go to step  8.
  7. Remove ECCS relay. See Fig 2. Check voltage between ground and fuse block relay cavity No. 3. If voltage exists, go to next step. If voltage does not exist, check 15-amp fuse and harness between relay and battery.
  8. Remove ECCS relay. Measure continuity of Red/Green wires between ECCS relay harness connector terminal No. 5 and PCM harness connector terminals No. 110 and 112. See Fig 3 and Figure . If continuity exists, go to next step. If continuity does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  9. Remove and test ECCS relay. Apply 12 volts to relay terminals No. 1 and 2. See Figure. Check continuity between relay terminal pairs No. 3 and 5 and 6 and 7. If continuity exists, go to next step. If continuity does not exist, replace ECCS relay.
  10. Disconnect PCM harness connector. Check continuity between ground and PCM harness connector terminal Nos. 48, 57, 106 and 108 (Black wires). If continuity exists, go to next step. If continuity does not exist, repair open or short in ground circuit(s).
  11. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
    Fig 3: Identifying PCM Harness Connector Terminals (Maxima & Sentra)
    G00015112Courtesy of NISSAN MOTOR CO., U.S.A.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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