ignition INFINITI QX56 2004 Factory Service Manual

DTC P0102, P0103 MAF SENSOR
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Revision: August 20072004 QX56
DTC Confirmation ProcedureUBS00H17
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.
PROCEDURE FOR DTC P0102
With CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Start engine and wait at least 5 seconds.
4. If DTC is detected, go to EC-157, "
Diagnostic Procedure" .
With GST
Follow the procedure “With CONSULT-II” above.
PROCEDURE FOR DTC P0103
With CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Wait at least 5 seconds.
4. If DTC is detected, go to EC-157, "
Diagnostic Procedure" .
If DTC is not detected, go to next step.
5. Start engine and wait at least 5 seconds.
6. If DTC is detected, go to EC-157, "
Diagnostic Procedure" .
With GST
Follow the procedure “With CONSULT-II” above.
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DTC P0102, P0103 MAF SENSOR
EC-157
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Revision: August 20072004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureUBS00H19
1. INSPECTION START
Which malfunction (P0102 or P0103) is duplicated?
P0102 or P0103
P0102 >> GO TO 2.
P0103 >> GO TO 3.
2. CHECK INTAKE SYSTEM
Check the following for connection.

Air duct

Vacuum hoses

Intake air passage between air duct to intake manifold
OK or NG
OK >> GO TO 3.
NG >> Reconnect the parts.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
51 W Mass air flow sensor[Engine is running]

Warm-up condition

Idle speed1.1 - 1.4V
[Engine is running]

Warm-up condition

Engine speed is 2,500 rpm.1.7 - 2.0V
67 B Sensor ground[Engine is running]

Warm-up condition

Idle speedApproximately 0V
111 W / BECM relay
(Self shut-off)[Engine is running]
[Ignition switch: OFF]

For a few seconds after turning ignition
switch OFF0 - 1.5V
[Ignition switch: OFF]

More than a few seconds after turning igni-
tion switch OFFBATTERY VOLTAGE
(11 - 14V)
11 9
120BR
BRPower supply for ECM[Ignition switch: ON]BATTERY VOLTAGE
(11 - 14V)

EC-158Revision: August 2007
DTC P0102, P0103 MAF SENSOR
2004 QX56
3. RETIGHTEN GROUND SCREWS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace ground connections.
4. CHECK MAF SENSOR POWER SUPPLY CIRCUIT
1. Disconnect mass air flow (MAF) sensor harness connector.
2. Turn ignition switch ON.
3. Check voltage between MAF sensor terminal 2 and ground with
CONSULT-II or tester.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors E2, F32

Harness for open or short between IPDM E/R and mass air flow sensor

Harness for open or short between mass air flow sensor and ECM
>> Repair harness or connectors.
BBIA0354E
BBIA0368E
Voltage: Battery voltage
PBIB11 68 E

DTC P0102, P0103 MAF SENSOR
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Revision: August 20072004 QX56
6. CHECK MAF SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between MAF sensor terminal 3 and ECM terminal 67.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
7. CHECK MAF SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between MAF sensor terminal 4 and ECM terminal 51.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 8.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
8. CHECK MASS AIR FLOW SENSOR
Refer to EC-160, "
Component Inspection" .
OK or NG
OK >> GO TO 9.
NG >> Replace mass air flow sensor.
9. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END Continuity should exist.
Continuity should exist.

EC-160Revision: August 2007
DTC P0102, P0103 MAF SENSOR
2004 QX56
Component InspectionUBS00H1A
MASS AIR FLOW SENSOR
1. Reconnect all harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 51 (Mass air flow sensor
signal) and ground.
*: Check for linear voltage rise in response to engine being increased to about
4,000 rpm.
4. If the voltage is out of specification, proceed the following.

Turn ignition switch OFF.

Disconnect mass air flow sensor harness connector and reconnect it again.

Perform steps 2 and 3 again.
5. If NG, remove mass air flow sensor from air duct. Check hot wire for damage or dust.
6. If NG, clean or replace mass air flow sensor.
Removal and InstallationUBS00H1B
MASS AIR FLOW SENSOR
Refer to EM-14, "AIR CLEANER AND AIR DUCT" .
Condition Voltage V
Ignition switch ON (Engine stopped.) Approx. 0.4
Idle (Engine is warmed-up to normal
operating temperature.)1.1 - 1.4
2,500 rpm (Engine is warmed-up to
normal operating temperature.)1.7 - 2.0
Idle to about 4,000 rpm* 1.1 - 1.4 to Approx. 4.0
PBIB11 06 E

DTC P0112, P0113 IAT SENSOR
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Revision: August 20072004 QX56
DTC P0112, P0113 IAT SENSORPFP:22630
Component DescriptionUBS00H1C
The intake air temperature sensor is built-into mass air flow sensor.
The sensor detects intake air temperature and transmits a signal to
the ECM.
The temperature sensing unit uses a thermistor which is sensitive to
the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.

*: This data is reference value and is measured between ECM terminal 34 (Intake air
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 LogicUBS00H1D
DTC Confirmation ProcedureUBS00H1E
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-163, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
BBIA0355E
Intake air temperature
°C (°F)Voltage* V Resistance kΩ
25 (77) 3.32 1.9 - 2.1
80 (176) 1.23 0.31 - 0.37
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DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0112
0112Intake air 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.)

Intake air temperature sensor P0113
0113Intake air temperature
sensor circuit high inputAn excessively high voltage from the sensor is
sent to ECM.
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DTC P0112, P0113 IAT SENSOR
EC-163
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Revision: August 20072004 QX56
Diagnostic ProcedureUBS00H1G
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2. CHECK INTAKE AIR TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Disconnect mass air flow sensor (intake air temperature sensor
is built-into) harness connector.
2. Turn ignition switch ON.
3. Check voltage between mass air flow sensor terminal 5 and
ground.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connectors.
BBIA0354E
BBIA0368E
Voltage: Approximately 5V
PBIB11 69 E

EC-164Revision: August 2007
DTC P0112, P0113 IAT SENSOR
2004 QX56
3. CHECK INTAKE AIR TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between mass air flow sensor terminal 6 and ECM terminal 67.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4. CHECK INTAKE AIR TEMPERATURE SENSOR
Refer to EC-164, "
Component Inspection" .
OK or NG
OK >> GO TO 5.
NG >> Replace mass air flow sensor (with intake air temperature sensor).
5. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00H1H
INTAKE AIR TEMPERATURE SENSOR
1. Check resistance between mass air flow sensor terminals 5 and
6 under the following conditions.
2. If NG, replace mass air flow sensor (with intake air temperature
sensor).
Removal and InstallationUBS00H1I
MASS AIR FLOW SENSOR
Refer to EM-14, "AIR CLEANER AND AIR DUCT" . Continuity should exist.
Intake air temperature °C (°F) Resistance kΩ
25 (77) 1.9 - 2.1
BBIA0355E
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DTC P0117, P0118 ECT SENSOR
EC-165
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Revision: August 20072004 QX56
DTC P0117, P0118 ECT SENSORPFP:22630
Component DescriptionUBS00H1J
The engine coolant temperature sensor is used to detect the engine
coolant temperature. The sensor modifies a voltage signal from the
ECM. The modified signal returns to the ECM as the engine coolant
temperature input. The sensor uses a thermistor which is sensitive to
the change in temperature. The electrical resistance of the ther-
mistor decreases as temperature increases.

*: This data is reference value and is measured between ECM terminal 73 (Engine
coolant 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 termi-
nals, such as the ground.
On Board Diagnosis LogicUBS00H1K
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
SEF 5 94 K
Engine coolant temperature
°C (°F)Voltage* V Resistance kΩ
20 (68) 3.5 2.1 - 2.9
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
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DTC
No.Trouble Diagnosis Name DTC Detecting Condition Possible Cause
P0117
0117Engine coolant 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.)

Engine coolant temperature sensor P0118
0118Engine coolant temperature
sensor circuit high inputAn excessively high voltage from the sensor is
sent to ECM.
Detected items Engine operating condition in fail-safe mode
Engine coolant temper-
ature sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch ON
or START.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided
(CONSULT-II display)
Just as ignition switch is turned ON or START 40°C (104°F)
More than approx. 4 minutes after ignition ON or
START80°C (176°F)
Except as shown above40 - 80°C (104 - 176°F)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates
while engine is running.

EC-166Revision: August 2007
DTC P0117, P0118 ECT SENSOR
2004 QX56
DTC Confirmation ProcedureUBS00H1L
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 DTC is detected, go to EC-168, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
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