Fuel Level Sensor Signal Inspection

Symptom:

• Fuel gauge indication is malfunction.
• Low-fuel warning lamp indication is irregular.

Fuel level sensor unit

• Depending on vehicle position or driving circumstance, the fuel level in the tank various, and the pointer may fluctuate.
• If the vehicle is fueled with the ignition switch ON, the pointer will move slowly.

Low-fuel warning lamp

• Depending on vehicle position or driving circumstance, the fuel in the tank flows and the warning lamp ON timing may change.

1. CHECK UNIFIED METER AND A/C AMP. INPUT SIGNAL 
   1. Select "METER A/C AMP" on CONSULT-II.
   2. Using "FUEL METER" on "DATA MONITOR", compare the value of "DATA MONITOR" with fuel gauge pointer of combination meter.
   DIAGNOSIS PROCEDURE
   
   

   Fuel gauge pointer	Reference value of data monitor [lit.]
   Full	Approx. 86
   Three quarters	Approx. 70
   Half	Approx. 48
   A quarter	Approx. 25
   Empty	Approx. 9

   Fig 1: CONSULT-II Diagnosis Function Display (5 Of 5)

   Courtesy of NISSAN MOTOR CO., U.S.A.

   OK or NG 

   1. OK: GO TO 2.
   2. NG: Replace combination meter.
2. CHECK FUEL LEVEL SENSOR 

   Check components. Refer to "CHECK FUEL LEVEL SENSOR UNIT ".

   OK or NG 

   1. OK: GO TO 3.
   2. NG: Replace fuel level sensor unit.
3. CHECK FUEL LEVEL SENSOR (SUB) CIRCUIT 
   1. Disconnect unified meter and A/C amp. connector and fuel level sensor unit (sub) connector.
   2. Check continuity between unified meter and A/C amp. harness connector M56 terminal 28 (W/B) and fuel level sensor unit (sub) harness connector B40 terminal 1 (LG).
      1. 28 (W/B) - 1 (LG): Continuity should exist. 
   3. Check continuity between unified meter and A/C amp. harness connector M56 terminal 28 (W/B) and ground.
      1. 28 (W/B) - Ground: Continuity should not exist. 

   OK or NG 

   1. OK: GO TO 4.
   2. NG: Repair harness or connector.
   Fig 2: Checking Continuity Between Terminal 28 And Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. CHECK FUEL LEVEL SENSOR (MAIN.SUB) CIRCUIT 
   1. Disconnect fuel level sensor unit and fuel pump (main) connector.
   2. Check continuity between fuel level sensor unit (sub) harness connector B40 terminal 2 (Y) and fuel level sensor unit and fuel pump (main) harness connector B39 terminal 2 (Y).
      1. 2 (Y) - 2 (Y): Continuity should exist. 
   3. Check continuity between fuel level sensor unit (sub) harness connector B40 terminal 2 (Y) and ground.
      1. 2 (Y) - Ground: Continuity should not exist. 

   OK or NG 

   1. OK: GO TO 5.
   2. NG: Repair harness or connector.
   Fig 3: Checking Continuity Between Terminal 2 And Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.
5. CHECK FUEL LEVEL SENSOR (MAIN) CIRCUIT 
   1. Check continuity between fuel level sensor unit and fuel pump (main) harness connector B39 terminal 5 (B) and unified meter and A/C amp. harness connector M56 terminal 36 (B/W).
      1. 5 (B) - 36 (B/W): Continuity should exist. 
   2. Check continuity between fuel level sensor unit and fuel pump (main) harness connector B39 terminal 5 (B) and ground.
      1. 5 (B) - Ground: Continuity should not exist. 

   OK or NG 

   1. OK: GO TO 6.
   2. NG: Repair harness or connector.
   Fig 4: Checking Continuity Between Terminal 5 And Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.
6. CHECK INSTALLATION CONDITION 

   Check fuel level sensor unit installation, and check whether the float arm interferes or binds with any of the internal components in the fuel tank.

   OK or NG 

   1. OK: Replace unified meter and A/C amp. Refer to "REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP. "
   2. NG: Install the fuel level sensor unit properly.