Fuel Level Sensor Signal Inspection

WARNING: This page is about a different car, the 2005 Nissan 350Z. However, it is still accessible from the selected car via links, so may be relevant.

Symptom:

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

NOTE: The following symptoms are not malfunction.

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.

CHECK UNIFIED METER AND A/C AMP. INPUT SIGNAL

Select "METER A/C AMP" on CONSULT-II.

Using "FUEL METER" on "DATA MONITOR", compare the value of "DATA MONITOR" with fuel gauge pointer of combination meter.

FUEL GAUGE INDICATION - VALUE ON MONITOR

Fuel gauge indication	Value on monitor [lit.]
Full	Approx. 74
Three quarters	Approx. 61
Half	Approx. 42
A quarter	Approx. 22
Empty	Approx. 8

Fig 1: Scan Tool Display "Data Monitor Fuel Meter"

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

OK or NG

OK : GO TO 2.
NG : Replace combination meter.

CHECK FUEL LEVEL SENSOR
1. Turn ignition switch OFF.
2. Check components. Refer to "FUEL LEVEL SENSOR UNIT CHECK ".
OK or NG
- OK : GO TO 3.
- NG : Replace fuel level sensor unit.
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 M49 terminal 28 (W/B) and fuel level sensor unit (sub) harness connector B28 terminal 1 (W/B).
  - 28 (W/B) - 1 (W/B) : Continuity should exist.
3. Check continuity between unified meter and A/C amp. harness connector M49 terminal 28 (W/B) and ground.
  - 28 (W/B) - Ground : Continuity should not exist.
  Fig 2: Unified Meter & A/C AMP. Harness Connector M49 Terminal 28 (W/B) & Ground Continuity Test
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK : GO TO 4.
- NG : Repair harness or connector.
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 B28 terminal 2 (Y) and fuel level sensor unit and fuel pump (main) harness connector B27 terminal 2 (Y).
  - 2 (Y) - 2 (Y) : Continuity should exist.
3. Check continuity between fuel level sensor unit (sub) harness connector B28 terminal 2 (Y) and ground.
  - 2 (Y) - Ground : Continuity should not exist.
  Fig 3: Fuel Level Sensor Unit (Sub) Harness Connector B28 Terminal 2 (Y) & Ground Continuity Test
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK : GO TO 5.
- NG : Repair harness or connector.
CHECK FUEL LEVEL SENSOR (MAIN) CIRCUIT
1. Check continuity between fuel level sensor unit and fuel pump (main) harness connector B27 terminal 5 (B/R) and unified meter and A/C amp. harness connector M49 terminal 36 (R/B).
  - 5 (B/R) - 36 (R/B) : Continuity should exist.
2. Check continuity between fuel level sensor unit and fuel pump (main) harness connector B27 terminal 5 (B/R) and ground.
  - 5 (B/R) - Ground : Continuity should not exist.
  Fig 4: Fuel Level Sensor Unit & Fuel Pump (Main) Harness Connector B27 Terminal 5 (B/R) & Ground Continuity Test
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK : GO TO 6.
- NG : Repair harness or connector.
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. Refer to "REMOVAL AND INSTALLATION OF UNIFIED METER AND A/C AMP. ".
- NG : Install the fuel level sensor unit properly.