Light INFINITI QX56 2004 Factory Service Manual

TROUBLE DIAGNOSIS
EC-109
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Revision: August 20072004 QX56P/N POSI SW
[ON/OFF]××
Indicates [ON/OFF] condition from the park/
neutral position (PNP) switch signal.
PW/ST SIGNAL
[ON/OFF]××

[ON/OFF] condition of the power steering sys-
tem (determined by the signal voltage of the
power steering pressure sensor signal) is indi-
cated.
LOAD SIGNAL
[ON/OFF]××

Indicates [ON/OFF] condition from the electri-
cal load signal.
ON: Rear window defogger switch is ON and/
or lighting switch is in 2nd position.
OFF: Both rear window defogger switch and
lighting switch are OFF.
IGNITION SW
[ON/OFF]

Indicates [ON/OFF] condition from ignition
switch signal.
HEATER FAN SW
[ON/OFF]

Indicates [ON/OFF] condition from the heater
fan switch signal.
BRAKE SW
[ON/OFF]

Indicates [ON/OFF] condition from the stop
lamp switch signal.
INJ PULSE-B1
[msec]×

Indicates the actual fuel injection pulse width
compensated by ECM according to the input
signals.
When the engine is stopped, a certain
computed value is indicated.
INJ PULSE-B2
[msec]
IGN TIMING
[BTDC]×

Indicates the ignition timing computed by ECM
according to the input signals.
When the engine is stopped, a certain
value is indicated.
CAL/LD VALUE [%]

“Calculated load value” indicates the value of
the current air flow divided by peak air flow.
MASS AIRFLOW
[g·m/s]

Indicates the mass air flow computed by ECM
according to the signal voltage of the mass air
flow sensor.
PURG VOL C/V
[%]

Indicates the EVAP canister purge volume
control solenoid valve control value computed
by the ECM according to the input signals.

The opening becomes larger as the value
increases.
AIR COND RLY
[ON/OFF]×

The air conditioner relay control condition
(determined by ECM according to the input
signals) is indicated.
FUEL PUMP RLY
[ON/OFF]×

Indicates the fuel pump relay control condition
determined by ECM according to the input sig-
nals.
VENT CONT/V
[ON/OFF]

The control condition of the EVAP canister
vent control valve (determined by ECM
according to the input signals) is indicated.
ON: Closed
OFF: Open
THRTL RELAY
[ON/OFF]

Indicates the throttle control motor relay con-
trol condition determined by the ECM accord-
ing to the input signals.
COOLING FAN
[HI/OFF]

The control condition of the cooling fan (deter-
mined by ECM according to the input signals)
is indicated.
ON: Operating
OFF: Stop Monitored item
[Unit]ECM
INPUT
SIG-
NALSMAIN
SIG-
NALSDescription Remarks

EC-112Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
ACTIVE TEST MODE
Test Item
*: Leaving cooling fan OFF with CONSULT-II while engine is running may cause the engine to overheat.
DTC & SRT CONFIRMATION MODE
SRT STATUS Mode
For details, refer to EC-55, "SYSTEM READINESS TEST (SRT) CODE" .
SRT Work Support Mode
This mode enables a technician to drive a vehicle to set the SRT while monitoring the SRT status.
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJEC-
TION

Engine: Return to the original
trouble condition

Change the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Harness and connectors

Fuel injector

Air fuel ratio (A/F) sensor 1
IGNITION TIM-
ING

Engine: Return to the original
trouble condition

Timing light: Set

Retard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Perform Idle Air Volume Learning.
POWER BAL-
ANCE

Engine: After warming up, idle
the engine.

A/C switch OFF

Shift lever N

Cut off each injector signal one at
a time using CONSULT-II.Engine runs rough or dies.

Harness and connectors

Compression

Fuel injector

Power transistor

Spark plug

Ignition coil
COOLING FAN*

Ignition switch: ON

Turn the cooling fan ON and OFF
using CONSULT-II.Cooling fan moves and stops.

Harness and connectors

Cooling fan motor

IPDM E/R
ENG COOLANT
TEMP

Engine: Return to the original
trouble condition

Change the engine coolant tem-
perature using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Harness and connectors

Engine coolant temperature sen-
sor

Fuel injector
FUEL PUMP
RELAY

Ignition switch: ON (Engine
stopped)

Turn the fuel pump relay ON and
OFF using CONSULT-II and lis-
ten to operating sound.Fuel pump relay makes the operat-
ing sound.
Harness and connectors

Fuel pump relay
PURG VOL
CONT/V

Engine: After warming up, run
engine at 1,500 rpm.

Change the EVAP canister purge
volume control solenoid valve
opening percent using CON-
SULT-II.Engine speed changes according to
the opening percent.
Harness and connectors

Solenoid valve
FUEL/T TEMP
SEN

Change the fuel tank temperature using CONSULT-II.
VENT CON-
TROL/V

Ignition switch: ON (Engine
stopped)

Turn solenoid valve ON and OFF
with the CONSULT-II and listen
to operating sound.Solenoid valve makes an operating
sound.
Harness and connectors

Solenoid valve

EC-118Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
CONSULT-II Reference Value in Data MonitorUBS00H07
Remarks:

Specification data are reference values.

Specification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show the specification data i n
spite of the ignition timing not being adjusted to the specification data. This IGN TIMING monitors the data calculated by the ECM
according to the signals input from the camshaft position sensor and other ignition timing related sensors.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEED

Run engine and compare the CONSULT-II value with tachometer indica-
tion.Almost the same speed as the
tachometer indication.
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
B/FUEL SCHDL

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

no loadIdle 3.0 - 4.2 msec
2,000 rpm 3.0 - 4.2 msec
A/F ALPHA-B1
A/F ALPHA-B2

Engine: After warming upMaintaining engine speed at 2,000
rpm54% - 155%
COOLAN TEMP/S

Engine: After warming up More than 70°C (158°F)
A/F SEN1 (B1)
A/F SEN1 (B2)

Engine: After warming upMaintaining engine speed at 2,000
rpmFluctuated around 1.5V
HO2S2 (B1)
HO2S2 (B2)

Warm-up condition

After keeping engine speed
between 3,500 and 4,000 rpm for
1 minute and at idle for 1 minute
under no load.Revving engine from idle to 3,000 rpm
quickly.0 - 0.3V ←→ Approx. 0.6 -
1.0V
HO2S2 MNTR (B1)
HO2S2 MNTR (B2)

Warm-up condition

After keeping engine speed
between 3,500 and 4,000 rpm for
1 minute and at idle for 1 minute
under no load.Revving engine from idle to 3,000 rpm
quickly.LEAN ←→ RICH
VEH SPEED SE

Turn drive wheels and compare the CONSULT-II value with speedometer
indication.Almost the same speed as the
speedometer indication
BATTERY VOLT

Ignition switch: ON (Engine stopped) 11 - 14V
ACCEL SEN1

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.0 - 4.7V
ACCEL SEN2*

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.3 - 1.2V
Accelerator pedal: Fully depressed 3.9 - 4.8V
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
EVAP SYS PRES

Ignition switch: ON Approx. 1.8 - 4.8V
START SIGNAL

Ignition switch: ON → START → ON OFF → ON → OFF
CLSD THL POS

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released ON
Accelerator pedal: Slightly depressed OFF
AIR COND SIG

Engine: After warming up, idle
the engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
P/N POSI SW

Ignition switch: ONShift lever: P or N ON
Shift lever: Except above OFF

TROUBLE DIAGNOSIS
EC-119
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Revision: August 20072004 QX56
PW/ST SIGNAL
Engine: After warming up, idle
the engineSteering wheel is in neutral position.
(Forward direction)OFF
Steering wheel is turned. ON
LOAD SIGNAL

Ignition switch: ONRear window defogger switch is ON
and/or lighting switch is in 2nd.ON
Rear window defogger switch is OFF
and lighting switch is OFF.OFF
IGNITION SW

Ignition switch: ON → OFF → ON ON → OFF → ON
HEATER FAN SW

Engine: After warming up, idle
the engineHeater fan is operating. ON
Heater fan is not operating OFF
BRAKE SW

Ignition switch: ONBrake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
INJ PULSE-B1
INJ PULSE-B2

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

no loadIdle 2.0 - 2.8 msec
2,000 rpm 1.9 - 2.9 msec
IGN TIMING

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

no loadIdle 14° - 18° BTDC
2,000 rpm 25° - 45° BTDC
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
PURG VOL C/V

Engine: After warming up

Air conditioner switch: OFF

Shift lever: N

no loadIdle
(Accelerator pedal is not depressed
even slightly, after starting engine)0%
2,000 rpm —
AIR COND RLY

Engine: After warming up, idle
the engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates)ON
FUEL PUMP RLY

For 1 second after turning ignition switch ON

Engine running or crankingON

Except above conditions OFF
VENT CONT/V

Ignition switch: ON OFF
THRTL RELAY

Ignition switch: ON ON
COOLING FAN

Engine: After warming up, idle
the engine

Air conditioner switch: OFFEngine coolant temperature is 99°C
(210°F) or lessOFF
Engine coolant temperature is
between 100°C (212°F) and 104°C
(219°F) at vehicle speed less than 40
km/h (25 MPH)ON
Engine coolant temperature is 105°C
(221°F) or moreON MONITOR ITEM CONDITION SPECIFICATION

EC-120Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
*: Accelerator pedal position sensor 2 signal and throttle position sensor 2 signal are converted by ECM internally. Thus, they differ from
ECM terminals voltage signal.HO2S2 HTR (B1)
HO2S2 HTR (B2)

Engine speed is below 3,600 rpm after the following conditions are met.
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no loadON

Engine speed: Above 3,600 rpm OFF
I/P PULLY SPD

Vehicle speed: More than 20 km/h (12 MPH)Almost the same speed as the
tachometer indication
VEHICLE SPEED

Turn drive wheels and compare the CONSULT-II value with speedometer
indication.Almost the same speed as the
speedometer indication
TRVL AFTER MIL

Ignition switch: ONVehicle has traveled after MIL has
turned ON.0 - 65,535 km
(0 - 40,723 miles)
AC PRESS SEN

Ignition switch: ON (Engine stopped) Approx. 0V

Engine: Idle

Air conditioner switch: OFF1.0 - 4.0V
VEH SPEED SE

Turn drive wheels and compare the CONSULT-II value with speedometer
indication.Almost the same speed as the
speedometer indication
SET VHCL SPD

Engine: Running ASCD: Operating.The preset vehicle speed is
displayed.
MAIN SW

Ignition switch: ONON/OFF(MAIN) switch: Pressed ON
ON/OFF(MAIN) switch: Released OFF
CANCEL SW

Ignition switch: ONCANCEL switch: Pressed ON
CANCEL switch: Released OFF
RESUME/ACC SW

Ignition switch: ONACCEL/RESUME switch: Pressed ON
ACCEL/RESUME switch: Released OFF
SET SW

Ignition switch: ONCOAST/SET switch: Pressed ON
COAST/SET switch: Released OFF
DIST SW

Ignition switch: ONDISTANCE switch: Pressed ON
DISTANCE switch: Released OFF
BRAKE SW1

Ignition switch: ONBrake pedal: Fully released ON
Brake pedal: Slightly depressed OFF
BRAKE SW2

Ignition switch: ONBrake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
CRUISE LAMP

Ignition switch: ONON/OFF(MAIN) switch: Pressed at the
1st time → at the 2nd timeON → OFF
SET LAMP

CRUISE switch: ON

When vehicle switch is between
40 km/h (25 MPH) and 144 km/h
(89 MPH).COAST/SET switch: Pressed ON
COAST/SET switch: Released OFF MONITOR ITEM CONDITION SPECIFICATION

TROUBLE DIAGNOSIS - SPECIFICATION VALUE
EC-123
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Revision: August 20072004 QX56
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

DTC U1000, U1001 CAN COMMUNICATION LINE
EC-135
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Revision: August 20072004 QX56
DTC U1000, U1001 CAN COMMUNICATION LINEPFP:23710
DescriptionUBS00H0I
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
On Board Diagnosis LogicUBS00H0J
*1: This self-diagnosis has the one trip detection logic.
*2: The MIL will not light up for this diagnosis.
DTC Confirmation ProcedureUBS00H0K
1. Turn ignition switch ON and wait at least 3 seconds.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. If 1st trip DTC is detected, go to EC-137, "
Diagnostic Procedure" .
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
U1000*
1
1000*1
CAN communication line

ECM cannot communicate to other control
units.

ECM cannot communicate for more than the
specified time.

Harness or connectors
(CAN communication line is open or
shorted) U1001*
2
1001*2

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 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
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.