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 varies, 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" to the indication of fuel gauge of combination meter.
   DATA MONITOR
   
   

   Fuel gauge pointer	Reference value of data monitor [lit.]
   Full	Approx. 74
   Three quarters	Approx. 61
   Half	Approx. 42
   A quarter	Approx. 22
   Empty	Approx. 8

   Fig 1: CONSULT-II Display - Data Meter

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

   OK or NG 

   OK: GO TO 2.

   NG: Replace combination meter.

2. CHECK FUEL LEVEL SENSOR 
   1. Turn ignition switch OFF.
   2. Check components. Refer to "CHECK FUEL LEVEL SENSOR UNIT ".

   OK or NG 

   OK: GO TO 3.

   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 (A) and fuel level sensor unit (sub) harness connector (B).
      UNIFIED METER AND A/C AMP. HARNESS CONNECTOR & FUEL LEVEL SENSOR UNIT (SUB) HARNESS CONNECTOR
      
      

      A		B		Continuity
      Connector	Terminal	Connector	Terminal
      M65	42	B52	1	Yes

      Fig 2: Checking Continuity Between Unified Meter And A/C Amp. Harness Connector And Fuel Level Sensor Unit

      Courtesy of NISSAN MOTOR CO., U.S.A.
   3. Check continuity between unified meter and A/C amp. harness connector (A) and ground.
      UNIFIED METER AND A/C AMP. HARNESS CONNECTOR AND GROUND
      
      

      A		Ground	Continuity
      Connector	Terminal
      M65	42		No

      OK or NG 

      OK: GO TO 4.

      NG: Repair harness or connector.

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 (A) and fuel level sensor unit and fuel pump (main) harness connector (B).
      FUEL LEVEL SENSOR UNIT (SUB) HARNESS CONNECTOR AND FUEL LEVEL SENSOR UNIT & FUEL PUMP (MAIN) HARNESS CONNECTOR
      
      

      A		B		Continuity
      Connector	Terminal	Connector	Terminal
      B52	2	B163	2	Yes

      Fig 3: Checking Continuity Between Fuel Level Sensor Unit Harness Connector And Fuel Level Sensor Unit

      Courtesy of NISSAN MOTOR CO., U.S.A.
   3. Check continuity between fuel level sensor unit (sub) harness connector (A) and ground.
   FUEL LEVEL SENSOR UNIT (SUB) HARNESS CONNECTOR AND GROUND
   
   

   A		Ground	Continuity
   Connector	Terminal
   B52	2		No

   OK or NG 

   OK: GO TO 5.

   NG: Repair harness or connector.

5. CHECK FUEL LEVEL SENSOR (MAIN) CIRCUIT 

   Check continuity between fuel level sensor unit and fuel pump (main) harness connector (A) and unified meter and A/C amp. harness connector (B).

   FUEL LEVEL SENSOR (MAIN) CIRCUIT
   
   

   A		B		Continuity
   Connector	Terminal	Connector	Terminal
   B163	5	M65	58	Yes

   Fig 4: Checking Continuity Between Fuel Level Sensor Unit And Fuel Pump (Main) Harness Connector

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

   OK or NG 

   OK: GO TO 6.

   NG: Repair harness or connector.

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 

   OK: Replace unified meter and A/C amp.

   NG: Install the fuel level sensor unit properly.