Electric INFINITI QX56 2004 Factory Service Manual

EC-86Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
Air Air duct
55555 5EM-14
Air cleanerEM-14
Air leakage from air duct
(Mass air flow sensor — electric
throttle control actuator)
5555EM-14
Electric throttle control actuatorEM-15
Air leakage from intake manifold/
Collector/GasketEM-15
Cranking Battery
111111
11SC-4
Generator circuitSC-17
Starter circuit 3SC-10
Signal plate 6EM-15
PNP switch 4AT- 1 0 9
Engine Cylinder head
55555 55 5EM-59
Cylinder head gasket 4 3
Cylinder block
66666 66 64
EM-73
Piston
Piston ring
Connecting rod
Bearing
Crankshaft
Va lv e
mecha-
nismTiming chain
55555 55 5EM-35
CamshaftEM-43
Intake valve
3EM-59
Exhaust valve
Exhaust Exhaust manifold/Tube/Muffler/
Gasket
55555 55 5EM-19
, EX-
3Three way catalyst
Lubrica-
tionOil pan/Oil strainer/Oil pump/Oil
filter/Oil gallery/Oil cooler
55555 55 5EM-22
, LU-
10 , LU-11
, LU-13
Oil level (Low)/Filthy oilLU-7
SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA

TROUBLE DIAGNOSIS
EC-115
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Revision: August 20072004 QX56
Operation
1. “AUTO TRIG”

While trying to detect the DTC/1st trip DTC by performing the DTC Confirmation Procedure, be sure to
select to “DATA MONITOR (AUTO TRIG)” mode. You can confirm the malfunction at the moment it is
detected.

While narrowing down the possible causes, CONSULT-II should be set in “DATA MONITOR (AUTO
TRIG)” mode, especially in case the incident is intermittent.
When you are inspecting the circuit by gently shaking (or twisting) the suspicious connectors, compo-
nents and harness in the DTC Confirmation Procedure, the moment a malfunction is found the DTC/1st
trip DTC will be displayed. (Refer to “INCIDENT SIMULATION TESTS” in GI-27, "
How to Perform Effi-
cient Diagnosis for an Electrical Incident" .)
2. “MANU TRIG”

If the malfunction is displayed as soon as “DATA MONITOR” is selected, reset CONSULT-II to “MANU
TRIG”. By selecting “MANU TRIG” you can monitor and store the data. The data can be utilized for fur-
ther diagnosis, such as a comparison with the value for the normal operating condition.
PBIB0197E

TROUBLE DIAGNOSIS - SPECIFICATION VALUE
EC-123
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TROUBLE DIAGNOSIS - SPECIFICATION VALUEPFP:00031
DescriptionUBS00H09
The specification (SP) value indicates the tolerance of the value that is displayed in “DATA MONITOR (SPEC)”
mode of CONSULT-II during normal operation of the Engine Control System. When the value in “DATA MONI-
TOR (SPEC)” mode is within the SP value, the Engine Control System is confirmed OK. When the value in
“DATA MONITOR (SPEC)” mode is NOT within the SP value, the Engine Control System may have one or
more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:

B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board cor-
rection)

A/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)

MAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Testing ConditionUBS00H0A

Vehicle driven distance: More than 5,000 km (3,017 miles)

Barometric pressure: 98.3 - 104.3 kPa (1.003 - 1.064 kg/cm2 , 14.25 - 15.12 psi)

Atmospheric temperature: 20 - 30°C (68 - 86°F)

Engine coolant temperature: 75 - 95°C (167 - 203°F)

Transmission: Warmed-up*1

Electrical load: Not applied*2

Engine speed: Idle
*1: After the engine is warmed up to normal operating temperature, drive vehicle until “FLUID TEMP SE” (A/T
fluid temperature sensor signal) indicates more than 60°C (140°F).
*2: Rear window defogger switch, air conditioner switch, lighting switch are OFF. Steering wheel is straight
ahead.
Inspection ProcedureUBS00H0B
NOTE:
Perform “DATA MONITOR (SPEC)” mode in maximum scale display.
1. Perform EC-79, "
Basic Inspection" .
2. Confirm that the testing conditions indicated above are met.
3. Select “B/FUEL SCHDL”, “A/F ALPHA-B1”, “A/F ALPHA-B2”
and “MAS A/F SE-B1” in “DATA MONITOR (SPEC)” mode with
CONSULT-II.
4. Make sure that monitor items are within the SP value.
5. If NG, go to EC-124, "
Diagnostic Procedure" .
SEF 6 01 Z

TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT
EC-127
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TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTPFP:00006
DescriptionUBS00H0D
Intermittent incidents (I/I) may occur. In many cases, the malfunction resolves itself (the part or circuit function
returns to normal without intervention). It is important to realize that the symptoms described in the customer's
complaint often do not recur on (1st trip) DTC visits. Realize also that the most frequent cause of I/I occur-
rences is poor electrical connections. Because of this, the conditions under which the incident occurred may
not be clear. Therefore, circuit checks made as part of the standard diagnostic procedure may not indicate the
specific malfunctioning area.
Common I/I Report Situations
Diagnostic ProcedureUBS00H0E
1. INSPECTION START
Erase (1st trip) DTCs. Refer to EC-62, "
HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMA-
TION" .
>> GO TO 2.
2. CHECK GROUND TERMINALS
Check ground terminals for corroding or loose connection.
Refer to GI-27, "
How to Perform Efficient Diagnosis for an Electrical Incident" , “CIRCUIT INSPECTION”,
“Ground Inspection”.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3. SEARCH FOR ELECTRICAL INCIDENT
Perform GI-27, "
How to Perform Efficient Diagnosis for an Electrical Incident" , “INCIDENT SIMULATION
TESTS”.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace.
4. CHECK CONNECTOR TERMINALS
Refer to GI-24, "
How to Check Terminal" , “HOW TO PROBE CONNECTORS”, “How to Check Enlarged Con-
tact Spring of Terminal”.
OK or NG
OK >>INSPECTION END
NG >> Repair or replace connector.
STEP in Work Flow Situation
II The CONSULT-II is used. The SELF-DIAG RESULTS screen shows time data other than [0] or [1t].
III The symptom described by the customer does not recur.
IV (1st trip) DTC does not appear during the DTC Confirmation Procedure.
VI The Diagnostic Procedure for PXXXX does not indicate the malfunctioning area.

POWER SUPPLY AND GROUND CIRCUIT
EC-133
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15. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminals 1, 115, 116 and ground.
Refer to Wiring Diagram.
3. Also check harness for short to power.
OK or NG
OK >> GO TO 17.
NG >> GO TO 16.
16. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors F32, E2

Harness for open or short between ECM and ground
>> Repair open circuit or short to power in harness or connectors.
17. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
OK or NG
OK >> Replace IPDM E/R.
NG >> Repair open circuit or short to power in harness or connectors.
Ground Inspection UBS00H0H
Ground connections are very important to the proper operation of electrical and electronic circuits. Ground
connections are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can
become an unwanted resistance. This unwanted resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drasti-
cally affect an electronically controlled circuit. A poor or corroded ground can easily affect the circuit. Even
when the ground connection looks clean, there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:

Remove the ground bolt or screw.

Inspect all mating surfaces for tarnish, dirt, rust, etc.

Clean as required to assure good contact.

Reinstall bolt or screw securely.

Inspect for “add-on” accessories which may be interfering with the ground circuit.

If several wires are crimped into one ground eyelet terminal, check for proper crimps. Make sure all of the
wires are clean, securely fastened and providing a good ground path. If multiple wires are cased in one
eyelet make sure no ground wires have excess wire insulation.Continuity should exist.

EC-146Revision: August 2007
DTC P0101 MAF SENSOR
2004 QX56
DTC P0101 MAF SENSORPFP:22680
Component DescriptionUBS00H0V
The mass air flow sensor is placed in the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor controls the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current supplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor ModeUBS00H0W
Specification data are reference values.
On Board Diagnosis LogicUBS00H0X
This self-diagnosis has the one trip detection logic.
BBIA0355E
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE-B1

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle Approx. 1.1 - 1.4V
2,500 rpm Approx. 1.7 - 2.0V
CAL/LD VALUE

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle 14% - 33%
2,500 rpm 12% - 25%
MASS AIRFLOW

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle 3.0 - 9.0 g·m/s
2,500 rpm 9.0 - 28.0 g·m/s
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0101
0101Mass air flow sensor circuit
range/performance problemA)A high voltage from the sensor is sent to ECM
under light load driving condition.

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

Mass air flow sensor
B)A low voltage from the sensor is sent to ECM
under heavy load driving condition.

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

Intake air leaks

Mass air flow sensor

EC-154Revision: August 2007
DTC P0102, P0103 MAF SENSOR
2004 QX56
DTC P0102, P0103 MAF SENSORPFP:22680
Component DescriptionUBS00H14
The mass air flow sensor is placed in the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor controls the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current supplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor ModeUBS00H15
Specification data are reference values.
On Board Diagnosis LogicUBS00H16
These self-diagnoses have the one trip detection logic.
FAIL -S AFE M OD E
When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.
BBIA0355E
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE-B1

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle Approx. 1.1 - 1.4V
2,500 rpm Approx. 1.7 - 2.0V
CAL/LD VALUE

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle 14% - 33%
2,500 rpm 12% - 25%
MASS AIRFLOW

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

No loadIdle 3.0 - 9.0 g·m/s
2,500 rpm 9.0 - 28.0 g·m/s
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0102
0102Mass air flow 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 leaks

Mass air flow sensor
P0103
0103Mass air flow sensor circuit
high inputAn excessively high voltage from the sensor is
sent to ECM.

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

Mass air flow sensor
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.

DTC P0112, P0113 IAT SENSOR
EC-161
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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.
<Reference data>
*: 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
SEF 0 12 P
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.
SEF 0 58 Y

DTC P0117, P0118 ECT SENSOR
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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.
<Reference data>
*: 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
SEF 0 12 P
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.

DTC P0122, P0123 TP SENSOR
EC-171
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DTC P0122, P0123 TP SENSORPFP:16119
Component DescriptionUBS00H1Q
Electric throttle control actuator consists of throttle control motor,
throttle position sensor, etc. The throttle position sensor responds to
the throttle valve movement.
The throttle position sensor has the two sensors. These sensors are
a kind of potentiometers which transform the throttle valve position
into output voltage, and emit the voltage signal to the ECM. In addi-
tion, these sensors detect the opening and closing speed of the
throttle valve and feed the voltage signals to the ECM. The ECM
judges the current opening angle of the throttle valve from these sig-
nals and the ECM controls the throttle control motor to make the
throttle valve opening angle properly in response to driving condi-
tion.
CONSULT-II Reference Value in Data Monitor ModeUBS00H1R
Specification data are reference values.
*: Throttle position sensor 2 signal is converted by ECM internally. Thus, it differs from ECM terminal voltage signal.
On Board Diagnosis LogicUBS00H1S
These self-diagnoses have the one trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.
PBIB0145E
MONITOR ITEM CONDITION SPECIFICATION
THRTL SEN1
THRTL SEN2*

Ignition switch: ON
(Engine stopped)

Shift lever: DAccelerator pedal: Fully released More than 0.36V
Accelerator pedal: Fully depressed Less than 4.75V
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0122
0122Throttle position sensor
2 circuit low inputAn excessively low voltage from the TP sensor
2 is sent to ECM.

Harness or connectors
(TP sensor 2 circuit is open or shorted.)
(APP sensor 2 circuit is shorted.)

Electric throttle control actuator
(TP sensor 2)

Accelerator pedal position sensor P0123
0123Throttle position sensor
2 circuit high inputAn excessively high voltage from the TP sen-
sor 2 is sent to ECM.
Engine operation condition in fail-safe mode
The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor.