2000 Infiniti QX4FACTORY OEM SERVICE PROCEDURE

Power & Ground Circuits (Quest)

  1. Start engine. If engine starts, turn engine off and go to next step. If engine does not start, turn ignition off and on. Measure voltage between ground and PCM harness connector terminal No. 24 (Blue/Yellow wire) by backprobing. See Figure and Fig 1 . If battery voltage exists, go to step  8. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
    Fig 1: Locating PCM Harness Connector & ECCS Relay (Quest)
    G97H06147Courtesy of NISSAN MOTOR CO., U.S.A.
  2. Measure voltage between ground and PCM harness connector terminal No. 80 (Yellow wire) by backprobing. See Figure. 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.
  3. While turning ignition on and off, measure voltage between ground and PCM harness connector terminals No. 67, 72 and 117 (Black/White wires) by backprobing. Battery voltage should exist for a few seconds after turning ignition off. If voltage is as specified, go to step  8. If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds, go to step  7.
  4. Disconnect ECCS relay harness connector. Measure voltage between ground and ECCS relay harness connector terminals No. 2 and 3 (Red wires). See Figure and Figure . 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.
  5. Disconnect PCM harness connector. Check continuity of White/Green wire between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1. See Figure and Figure . If continuity exists, go to next step. If continuity does not exist, repair open in White/Green wire.
  6. Check continuity of Black/White wires between ECCS relay harness connector terminal No. 5 and PCM harness connector terminals No. 67, 72 and 117. See Figure and Figure . If continuity exists, go to next step. If continuity does not exist, repair open in Black/White wire(s).
  7. Check ECCS relay. See RELAYS  under RELAYS & SOLENOIDS. Replace, if necessary and retest system. If relay is okay, go to next step.
  8. Turn ignition off. Disconnect PCM harness connector. Check continuity between ground and PCM harness connector terminals No. 10, 19, 116 and 124 (Black wires) and terminals No. 25 and 32 (Black/Red wires). If continuity exists, go to next step. If continuity does not exist, repair open ground circuit(s).
  9. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.