Diagnosis Procedure

WARNING: This page is about a different car, the 2008 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.

CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to , "GROUND INSPECTION ".

Fig 1: Identifying Ground Connections
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG

OK: GO TO 2.

NG: Repair or replace ground connections.
CHECK FPCM POWER SUPPLY CIRCUIT
1. Disconnect fuel pump control module (FPCM) harness connector.
  
  Fig 2: Identifying Fuel Pump Control Module (FPCM) Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
2. Turn ignition switch ON.
3. Check voltage between FPCM terminal 4 and ground with CONSULT-III or tester.
Voltage: Battery voltage

Fig 3: Checking Voltage Between FPCM Terminal 4 And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG

OK: GO TO 4.

NG: GO TO 3.
DETECT MALFUNCTIONING PART
Check the following.
- Harness for open or short between FPCM and IPDM E/R
Repair open circuit or short to ground or short to power in harness or connectors.
CHECK FPCM GROUND CIRCUIT-I FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Check harness continuity between FPCM terminal 1 and ground.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
3. Also check harness for short to power.
OK or NG

OK: GO TO 5.

NG: Repair open circuit or short to power in harness or connectors.
CHECK FPCM GROUND CIRCUIT-II FOR OPEN AND SHORT
1. Disconnect "fuel level sensor unit and fuel pump" harness connector.
2. Disconnect dropping resistor harness connector.
3. Check harness continuity between the following; "fuel level sensor unit and fuel pump" terminal 3 and dropping resistor terminal 2,
  FPCM terminal 2 and dropping resister terminal 2.
  
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
  
  Fig 4: Checking Fuel Pump Power Supply And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
4. Check harness continuity between the following;
  FPCM terminal 2 and ground, "fuel level sensor and fuel pump" terminal 3 and ground.
  
  Refer to WIRING DIAGRAM .
  
  Continuity should not exist.
5. Also check harness for short to power.
OK or NG

OK: GO TO 7.

NG: GO TO 6.
DETECT MALFUNCTIONING PART
Check the following.
- Harness for open or short between "fuel level sensor unit and fuel pump" and dropping resistor
- Harness connectors C1, E41
- Harness for open or short between FPCM and dropping resistor
- Harness for short between "fuel level sensor unit and fuel pump" and ground
- Harness for short between FPCM and ground
Repair open circuit or short to ground or short to power in harness or connectors.
CHECK FPCM INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 38 and FPCM terminal 2.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
3. Check harness continuity between ECM terminal 38 and ground.
  Refer to WIRING DIAGRAM .
  
  Continuity should not exist.
4. Also check harness for short to power.
OK or NG

OK: GO TO 9.

NG: GO TO 8.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F32, E2
- Harness for open or short between ECM and FPCM
Repair open circuit or short to ground or short to power in harness or connectors.
CHECK FPCM OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 39 and FPCM terminal 3.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG

OK: GO TO 11.

NG: GO TO 10.
DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F32, E2
- Harness for open or short between ECM and FPCM
Repair open circuit or short to ground or short to power in harness or connectors.
CHECK FPCM
Refer to , "COMPONENT INSPECTION ".

OK or NG

OK: GO TO 12.

NG: Replace FPCM.
CHECK INTERMITTENT INCIDENT
Refer to "HOW TO CHECK TERMINAL " and "INTERMITTENT INCIDENT ".

INSPECTION END