sensor INFINITI QX4 2005 Factory Service Manual

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-251
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-93, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-94, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to EC-637, "FUEL PUMP CIRCUIT" .)

Fuel pressure regulator (Refer to EC-94, "FUEL PRESSURE CHECK" .)
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
OK or NG
OK >> GO TO 7.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to EC-174, "
DTC P0101 MAF SENSOR" . At idling: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm

DTC P0181 FTT SENSOR
EC-253
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
DTC P0181 FTT SENSORPFP:22630
Component DescriptionUBS00H34
The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.

*: This data is reference value and is measured between ECM terminal 107 (Fuel
tank temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output
voltage. Doing so may result in damage to the ECM's transistor.
Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicUBS00H35
DTC Confirmation ProcedureUBS00H36
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Wait at least 10 seconds.
If the result is NG, go to EC-256, "
Diagnostic Procedure" .
If the result is OK, go to following step.
4. Check “COOLAN TEMP/S” value.
If “COOLAN TEMP/S” is less than 60°C (140°F), the result will
be OK.
If “COOLAN TEMP/S” is above 60°C (140°F), go to the following
step.
5. Cool engine down until “COOLAN TEMP/S” is less than 60°C
(140°F).
6. Wait at least 10 seconds.
7. If 1st trip DTC is detected, go to EC-256, "
Diagnostic Procedure" .
BBIA0583E
Fluid temperature
°C (°F)Voltage*
VResistance
kΩ
20 (68) 3.5 2.3 - 2.7
50 (122) 2.2 0.79 - 0.90
SEF 0 12 P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0181
0181Fuel tank temperature
sensor circuit range/
performanceRationally incorrect voltage from the sensor is
sent to ECM, compared with the voltage sig-
nals from engine coolant temperature sensor
and intake air temperature sensor.

Harness or connectors
(The sensor circuit is open or shorted)

Fuel tank temperature sensor
SEF 1 74 Y

EC-254Revision: October 2005
DTC P0181 FTT SENSOR
2005 QX56
WITH GST
Follow the procedure “WITH CONSULT-II” above.

DTC P0181 FTT SENSOR
EC-255
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
Wiring DiagramUBS00H37
BBWA1682E

EC-256Revision: October 2005
DTC P0181 FTT SENSOR
2005 QX56
Diagnostic ProcedureUBS00H38
1. CHECK COMBINATION METER FUNCTION
Refer to DI-5, "
COMBINATION METERS" .
OK or NG
OK >> GO TO 2.
NG >> Go to DI-22, "
Fuel Level Sensor Unit Inspection" .
2. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-162, "
Ground Inspection" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace ground connections.
3. CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Disconnect “fuel level sensor unit and fuel pump” harness con-
nector.
2. Turn ignition switch ON.
3. Check voltage between “fuel level sensor unit and fuel pump”
terminal 4 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
BBIA0354E
BBIA0583E
Voltage: Approximately 5V
PBIB0932E

DTC P0181 FTT SENSOR
EC-257
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
4. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors C1, E41

Harness for open or short between ECM and “fuel level sensor unit and fuel pump”
>> Repair harness or connector.
5. CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect combination meter harness connector.
3. Check harness continuity between “fuel level sensor unit and fuel pump” terminal 3 and combination
meter terminal 16. Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
6. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors C1, E41

Harness connectors E152, M31

Harness for open or short between “fuel level sensor unit and fuel pump” and combination meter
>> Repair open circuit or short to ground or short to power in harness or connector.
7. CHECK FUEL TANK TEMPERATURE SENSOR
Refer to EC-258, "
Component Inspection" .
OK or NG
OK >> GO TO 8.
NG >> Replace “fuel level sensor unit and fuel pump”.
8. CHECK INTERMITTENT INCIDENT
Refer to EC-156, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END Continuity should exist.

EC-258Revision: October 2005
DTC P0181 FTT SENSOR
2005 QX56
Component InspectionUBS00H39
FUEL TANK TEMPERATURE SENSOR
1. Remove fuel level sensor unit.
2. Check resistance between “fuel level sensor unit and fuel pump”
terminals 3 and 4 by heating with hot water or heat gun as
shown in the figure.
Removal and InstallationUBS00H3A
FUEL TANK TEMPERATURE SENSOR
Refer to FL-5, "FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY" .
Temperature °C (°F) Resistance kΩ
20 (68) 2.3 - 2.7
50 (122) 0.79 - 0.90
SEF 4 76 YA

DTC P0182, P0183 FTT SENSOR
EC-259
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
DTC P0182, P0183 FTT SENSORPFP:22630
Component DescriptionUBS00H3B
The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.

*: This data is reference value and is measured between ECM terminal 107 (Fuel
tank temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output
voltage. Doing so may result in damage to the ECM's transistor.
Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicUBS00H3C
DTC Confirmation ProcedureUBS00H3D
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Wait at least 5 seconds.
4. If 1st trip DTC is detected, go to EC-261, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
BBIA0583E
Fluid temperature
°C (°F)Voltage*
VResistance
kΩ
20 (68) 3.5 2.3 - 2.7
50 (122) 2.2 0.79 - 0.90
SEF 0 12 P
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0182
0182Fuel tank temperature
sensor circuit low inputAn excessively low voltage from the sensor is
sent to ECM.

Harness or connectors
(The sensor circuit is open or shorted.)

Fuel tank temperature sensor P0183
0183Fuel tank temperature
sensor circuit high inputAn excessively high voltage from the sensor is
sent to ECM.
SEF 1 74 Y

EC-260Revision: October 2005
DTC P0182, P0183 FTT SENSOR
2005 QX56
Wiring DiagramUBS00H3E
BBWA1682E

DTC P0182, P0183 FTT SENSOR
EC-261
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
Diagnostic ProcedureUBS00H3F
1. CHECK COMBINATION METER FUNCTION
Refer to DI-5, "
COMBINATION METERS" .
OK or NG
OK >> GO TO 2.
NG >> Go to DI-22, "
Fuel Level Sensor Unit Inspection" .
2. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-162, "
Ground Inspection" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace ground connections.
3. CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Disconnect “fuel level sensor unit and fuel pump” harness con-
nector.
2. Turn ignition switch ON.
3. Check voltage between “fuel level sensor unit and fuel pump”
terminal 4 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
BBIA0354E
BBIA0583E
Voltage: Approximately 5V
PBIB0932E