Fuel Level Sensor Signal Inspection

Fuel level sensor unit

• Depending on vehicle posture 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 posture or driving circumstance, the fuel level in the tank varies, and the warning lamp ON timing may be changed.

1. CHECK HARNESS CONNECTOR 

   Check combination meter, fuel level sensor unit and terminals (meter side, module side, lead side, and harness side) for poor connection and bend.

   OK or NG 

   1. OK: GO TO 2.
   2. NG: Repair terminal or connector.
2. CHECK HARNESS CONNECTOR OUTPUT SIGNAL 
   1. Turn ignition switch OFF.
   2. Disconnect fuel level sensor unit connector.
   3. Turn ignition switch ON.
   4. Check voltage between combination meter harness connector M42 terminal 30 (R/L) and ground.
      1. 30 (R/L) - Ground: Approx. 5 V 

   OK or NG 

   1. OK: GO TO 3.
   2. NG: Replace combination meter.
   Fig 1: Disconnecting Fuel Level Sensor Unit Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. CHECK FUEL LEVEL SENSOR OPEN CIRCUIT 
   1. Turn ignition switch OFF.
   2. Disconnect combination meter connector.
   3. Check continuity between combination meter harness connector M42 terminals 29 (B/Y), 30 (R/L) and fuel level sensor unit harness connector B239 terminals 6 (B), 5 (R/L).
      1. 29 (B/Y) - 6 (B) 
      2. 30 (R/L) - 5 (R/L): Continuity should exist. 

   OK or NG 

   1. OK: GO TO 4.
   2. NG: Repair harness or connector.
   Fig 2: Checking Fuel Level Sensor Open Circuit Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. CHECK FUEL LEVEL SENSOR SHORT CIRCUIT 

   Check continuity between combination meter harness connector M42 terminals 29 (B/Y), 30 (R/L) and ground.

   1. 29 (B/Y) - Ground: Continuity should not exist. 
   2. 30 (R/L) - Ground 

   OK or NG 

   1. OK: GO TO 5.
   2. NG: Repair harness or connector.
   Fig 3: Identifying Fuel Level Sensor Short Circuit

   Courtesy of NISSAN MOTOR CO., U.S.A.
5. CHECK FUEL LEVEL SENSOR UNIT 

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

   OK or NG 

   1. OK: GO TO 6.
   2. NG: Replace fuel level sensor unit.
6. CHECK INSTALLATION CONDITION 

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

   OK or NG 

   1. OK: Replace combination meter.
   2. NG: Install fuel level sensor unit properly.