2000 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE

Fuel Pump Control System (G20)

  1. Turn ignition on. Pinch fuel hose (at filter outlet) 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 No. 1 harness connector. See Figure. Turn ignition on. Measure voltage between ground and fuel pump relay No. 1 harness connector terminal No. 1 (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. Measure voltage between ground and fuel pump relay No. 1 harness connector terminal No. 3 (Black/Red wire). If battery voltage exists, go to step  8. If battery voltage does not exist, go to next step.
  4. Turn ignition off. Disconnect fuel pump relay No. 2 harness connector. See Fig 1. Turn ignition on. Measure voltage between ground and fuel pump relay No. 2 harness connector terminals No. 1 (Black/White wire) and No. 3 (Black/Orange 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.
  5. Turn ignition off. Check continuity of Black/Red wire between fuel pump relay No. 2 harness connector terminal No. 5 and fuel pump relay No. 1 harness connector terminal No. 3. 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 continuity between body ground and fuel pump relay No. 2 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.
  7. Check fuel pump relay No. 2. See RELAYS & SOLENOIDS . Replace, if necessary and retest system. If relay is okay, go to next step.
  8. Turn ignition off. Disconnect fuel pump harness connector located behind access cover, under rear seat. Check continuity of Black/Yellow wire between fuel pump harness connector terminal No. 1 and fuel pump relay No. 1 harness connector terminal No. 5. 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.
  9. Check continuity between body ground and fuel pump 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.
  10. Disconnect ECM harness connector. See Figure. Check continuity of Black/Pink wire between ECM harness connector terminal No. 21 and fuel pump relay No. 1 harness connector terminal No. 2. 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.
  11. Check fuel pump relay No. 1. See RELAYS & SOLENOIDS . Replace, if necessary and retest system. If relay is okay, go to next step.
  12. Measure resistance between fuel pump terminals. 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.
  13. 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 Relay No. 2 (G20)
G00010133Courtesy 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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