1999 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE

Fuel Pump Control System (Q45)

  1. Turn ignition on. Pinch fuel hose with fingers. For 5 seconds after ignition is turned on, pulsation should be felt on fuel hose. If pulsation is felt, system is okay. If pulsation is not felt, go to next step.
  2. Turn ignition off. Disconnect fuel pump relay. See Figure. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (White wire) and No. 3 (Black/White wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See appropriate diagram in WIRING DIAGRAMS article.
  3. Turn ignition off. Disconnect fuel pump, Fuel Pump Control Module (FPCM) and dropping resistor harness connectors. See Fig 1 and Fig 2. Fuel pump harness connector is located in bottom of trunk. Check continuity of Black/Yellow wire between fuel pump relay harness connector terminal No. 5, FPCM harness connector terminal No. 3 and fuel pump harness connector terminal No. 1. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Yellow wire.
  4. Check continuity between ground and dropping resistor harness connector Black wire. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire.
  5. Disconnect PCM harness connector. See Figure. Check continuity of Black/Pink wire between fuel pump relay harness connector terminal No. 2 and PCM harness connector terminal No. 42. See Figure. If continuity exists, go to next step. If continuity does not exist, repair open in Black/Pink wire.
  6. Check fuel pump relay. See RELAYS & SOLENOIDS . Replace if necessary. If fuel pump relay is okay, check fuel pump. See FUEL PUMP . Replace if necessary. If fuel pump is okay, go to next step.
  7. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
Fig 1: Locating Fuel Pump Control Module (FPCM) Harness Connector (Q45)
G97C06692Courtesy 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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