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Home >> Infiniti >> 2001 >> Q45 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Fuel System >> Fuel Delivery >> Fuel Pump Control System (Q45)
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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 No. 1. 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 step  4. If battery voltage does not exist, go to next step.
  3. Check the following and repair as necessary:
    • Fuel pump relay No. 2 located next to fuel pump relay No. 1. See RELAYS & SOLENOIDS .
    • Fuse No. 29 (15-amp) located in instrument panel junction block.
    • Fuse No 15 (15-amp) located in engine compartment fuse and fusible link box.
    • White wire between instrument panel junction block and fuel pump relay No. 2 harness connector terminal No. 1 for open or short.
    • White/Red wire between engine compartment fuse and fusible link box and fuel pump relay No. 2 harness connector terminal No. 3 for open or short.
    • Black/White wire between fuel pump relay No. 2 harness connector terminal No. 5 and fuel pump relay No. 1 harness connector terminal No. 3 for open or short.
    • Black wire between fuel pump relay No. 2 and ground for open or short.

    To identify relays and wires, see WIRING DIAGRAMS article.

  4. 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 No. 1 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 circuit as necessary and retest system. If circuit is okay, go to next step.
  5. 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.
  6. Disconnect ECM harness connector. See Figure. Check continuity of Black/Pink wire between fuel pump relay No. 1 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 circuit as necessary and retest system. If circuit is okay, go to next step.
  7. Check fuel pump relay No. 1. See RELAYS & SOLENOIDS . Replace, if necessary and retest system. If relay is okay, go to next step.
  8. Measure resistance between fuel pump terminals No. 1 and 3. See Fig 3. 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.
  9. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating Fuel Pump Control Module (Q45)
G00025006Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating Dropping Resistor (Q45)
G99J05950Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Checking Fuel Pump Resistance (Q45)
G96B10786Courtesy of NISSAN MOTOR CO., U.S.A.
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