2000 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE

Fuel Pump Control System (Q45)

  1. Turn ignition on. Pinch fuel hose (before fuel damper) 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 and retest system. See appropriate wiring diagram in WIRING DIAGRAMS article.
  3. Turn ignition off. Disconnect fuel pump, Fuel Pump Control Module (FPCM) and dropping resistor harness connectors. See Fig 2 and Fig 3. 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. Also check circuit for short to ground and short to voltage. Repair as necessary and retest system. If circuit is okay, go to next step.
  4. Check continuity between body ground and dropping resistor harness connector terminal No. 2 (Black wire). Also check circuit for short to voltage. Repair as necessary and retest system. If ground circuit is okay, go to next step.
  5. Disconnect ECM harness connector. See Figure. Check continuity of Black/Pink wire between fuel pump relay harness connector terminal No. 2 and ECM harness connector terminal No. 42. See Figure. Also check circuit for short to ground and short to voltage. Repair as necessary and retest system. If circuit is okay, go to next step.
  6. Check fuel pump relay. See RELAYS & SOLENOIDS . Replace, if necessary and retest system. If fuel pump relay is okay, go to next step.
  7. Measure resistance between fuel pump terminals No. 1 and 3. See Fig 1. Resistance should be 0.2-5.0 ohms at 77°F (25°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump and retest system.
  8. 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: Checking Fuel Pump Resistance (Q45)
G96B10786Courtesy 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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