Air INFINITI QX56 2004 Factory Service Manual

EC-78Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56

When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting MIL up when
there is malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected
as NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by
means of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MIL circuit are detected, and demands
the driver to repair the malfunction.
P0122
P0123
P0222
P0223
P2135Throttle position sensor 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.
P1121 Electric throttle control
actuator(When electric throttle control actuator does not function properly due to the return spring
malfunction:)
ECM controls the electric throttle actuator by regulating the throttle opening around the
idle position. The engine speed will not rise more than 2,000 rpm.
(When throttle valve opening angle in fail-safe mode is not in specified range:)
ECM controls the electric throttle control actuator by regulating the throttle opening to 20
degrees or less.
(When ECM detects the throttle valve is stuck open:)
While the vehicle is driving, it slows down gradually by fuel cut. After the vehicle stops,
the engine stalls.
The engine can restart in N or P position, and engine speed will not exceed 1,000 rpm or
more.
P1122 Electric throttle control
functionECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P1124
P1126Throttle control motor relay ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P1128 Throttle control motor ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P1229 Sensor power supply ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
P2122
P2123
P2127
P2128
P2138Accelerator pedal position
sensorThe 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. DTC No. Detected items Engine operating condition in fail-safe mode
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut

TROUBLE DIAGNOSIS
EC-79
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Revision: August 20072004 QX56
Basic InspectionUBS00GZZ
1. INSPECTION START
1. Check service records for any recent repairs that may indicate a related malfunction, or a current need for
scheduled maintenance.
2. Open engine hood and check the following:
–Harness connectors for improper connections
–Wiring harness for improper connections, pinches and cut
–Vacuum hoses for splits, kinks and improper connections
–Hoses and ducts for leaks
–Air cleaner clogging
–Gasket
3. Confirm that electrical or mechanical loads are not applied.
–Head lamp switch is OFF.
–Air conditioner switch is OFF.
–Rear window defogger switch is OFF.
–Steering wheel is in the straight-ahead position, etc.
4. Start engine and warm it up until engine coolant temperature
indicator points the middle of gauge.
Ensure engine stays below 1,000 rpm.
5. Run engine at about 2,000 rpm for about 2 minutes under no
load.
6. Make sure that no DTC is displayed with CONSULT-II or GST.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. REPAIR OR REPLACE
Repair or replace components as necessary according to corresponding Diagnostic Procedure.
>> GO TO 3.
SEF 9 83 U
SEF 9 76 U
SEF 9 77 U

TROUBLE DIAGNOSIS
EC-81
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Revision: August 20072004 QX56
6. PERFORM IDLE AIR VOLUME LEARNING
Refer to EC-44, "
Idle Air Volume Learning" .
Is Idle Air Volume Learning carried out successfully?
Ye s o r N o
Yes >> GO TO 7.
No >> 1. Follow the instruction of Idle Air Volume Learning.
2. GO TO 4.
7. CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Read idle speed in “DATA MONITOR” mode with CONSULT-II.
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
OK or NG
OK >> GO TO 10.
NG >> GO TO 8.
8. DETECT MALFUNCTIONING PART
Check the following.

Check camshaft position sensor (PHASE) and circuit. Refer to EC-261 .

Check crankshaft position sensor (POS) and circuit. Refer to EC-255 .
OK or NG
OK >> GO TO 9.
NG >> 1. Repair or replace.
2. GO TO 4.
9. CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but
this is a rare case.)
2. Perform initialization of IVIS (NATS) system and registration of all IVIS (NATS) ignition key IDs. Refer to
BL-138, "
IVIS (INFINITI VEHICLE IMMOBILIZER SYSTEM-NATS)" .
>> GO TO 4. 650 ± 50 rpm (in P or N position)
650 ± 50 rpm (in P or N position)

EC-82Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
10. CHECK IGNITION TIMING
1. Run engine at idle.
2. Check ignition timing with a timing light.
OK or NG
OK >>INSPECTION END
NG >> GO TO 11.
11 . PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING
1. Stop engine.
2. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
>> GO TO 12.
12. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING
Perform EC-44, "
Throttle Valve Closed Position Learning" .
>> GO TO 13.
13. PERFORM IDLE AIR VOLUME LEARNING
Refer to EC-44, "
Idle Air Volume Learning" .
Is Idle Air Volume Learning carried out successfully?
Ye s o r N o
Yes >> GO TO 14.
No >> 1. Follow the instruction of Idle Air Volume Learning.
2. GO TO 4.
14. CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Read idle speed in “DATA MONITOR” mode with CONSULT-II.
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
OK or NG
OK >> GO TO 15.
NG >> GO TO 17.15 ± 5° BTDC (in P or N position)
BBIA0379E
650 ± 50 rpm (in P or N position)
650 ± 50 rpm (in P or N position)

TROUBLE DIAGNOSIS
EC-83
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15. CHECK IGNITION TIMING AGAIN
1. Run engine at idle.
2. Check ignition timing with a timing light.
OK or NG
OK >>INSPECTION END
NG >> GO TO 16.
16. CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-35, "
TIMING CHAIN" .
OK or NG
OK >> GO TO 17.
NG >> 1. Repair the timing chain installation.
2. GO TO 4.
17. DETECT MALFUNCTIONING PART
Check the following.

Check camshaft position sensor (PHASE) and circuit. Refer to EC-261 .

Check crankshaft position sensor (POS) and circuit. Refer to EC-255 .
OK or NG
OK >> GO TO 18.
NG >> 1. Repair or replace.
2. GO TO 4.
18. CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but
this is a rare case.)
2. Perform initialization of IVIS (NATS) system and registration of all IVIS (NATS) ignition key IDs. Refer to
BL-138, "
IVIS (INFINITI VEHICLE IMMOBILIZER SYSTEM-NATS)" .
>> GO TO 4. 15 ± 5° BTDC (in P or N position)
BBIA0379E

EC-84Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
Symptom Matrix ChartUBS00H00
SYSTEM — BASIC ENGINE CONTROL SYSTEM
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
Fuel Fuel pump circuit 1 1 2 3 2 2 2 3 2EC-601
Fuel pressure regulator system 3 3 4 4 4 4 4 4 4 4EC-46
Injector circuit 1 1 2 3 2 2 2 2EC-595
Evaporative emission system 3 3 4 4 4 4 4 4 4 4EC-633
Air Positive crankcase ventilation sys-
tem
334444444 41EC-645
Incorrect idle speed adjustment 1 1 1 1 1EC-79
Electric throttle control actuator 1 1 2 3 3 2 2 2 2 2 2EC-365,
EC-367
Ignition Incorrect ignition timing adjustment 3 3 1 1 1 1 1 1EC-79
Ignition circuit 1 1 2 2 2 2 2 2EC-583
Main power supply and ground circuit 2 2 3 3 3 3 3 2 3EC-128
Mass air flow sensor circuit
1
122
222 2EC-146,
EC-154
Engine coolant temperature sensor circuit
333EC-165,
EC-178
A/F sensor 1 circuitEC-429
,
EC-437
,
EC-445
,
EC-454
,
EC-463
,
EC-472
,
EC-484
Throttle position sensor circuit
22EC-171
,
EC-236
,
EC-420
,
EC-422
,
EC-569
Accelerator pedal position sensor circuit 3 2 1EC-424
,
EC-556
,
EC-562
,
EC-576
Knock sensor circuit 2 3EC-250
Crankshaft position sensor (POS) circuit 2 2EC-255
Camshaft position sensor (PHASE) circuit 3 2EC-261

TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
1 - 6: The numbers refer to the order of inspection.
(continued on next page)
SYSTEM — ENGINE MECHANICAL & OTHER
Vehicle speed signal circuit 2 3 3 3EC-340
Power steering pressure sensor circuit 2 3 3EC-346
ECM 22333333333EC-351,
EC-361
PNP switch circuit 3 3 3 3 3EC-546
Refrigerant pressure sensor circuit 2 3 3 4EC-607
Electrical load signal circuit 3EC-612
Air conditioner circuit 2 2 3 3 3 3 3 3 3 3 2AT C - 3 3
ABS actuator and electric unit (control unit) 4BRC-11
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
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
Fuel Fuel tank
5
5FL-9
Fuel piping 5 5 5 5 5 5FL-3
Vapor lock—
Valve deposit
555555 5—
Poor fuel (Heavy weight gaso-
line, Low octane)—

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
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Revision: August 20072004 QX56
25 O/GHeated oxygen sensor 2
heater (bank 2)[Engine is running]

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 load.0 - 1.0V
[Ignition switch: ON]

Engine stopped
[Engine is running]

Engine speed is above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)
32 LEVAP control system pres-
sure sensor[Ignition switch: ON]Approximately 1.8 - 4.8V
34 R/BIntake air temperature sen-
sor[Engine is running]Approximately 0 - 4.8V
Output voltage varies with intake
air temperature.
36 W Knock sensor 2[Engine is running]

Idle speedApproximately 2.5V
45 L/YEVAP canister purge volume
control solenoid valve[Engine is running]

Idle speed

Accelerator pedal is not depressed even
slightly, after starting engine.BATTERY VOLTAGE
(11 - 14V)
[Engine is running]

Engine speed is about 2,000 rpm (More
than 100 seconds after starting engine).11 - 14V
46
60
61
62
65
79
80
81L/R
GR/R
O/W
Y/R
G/R
V/W
W/R
W/GIgnition signal No. 7
Ignition signal No. 5
Ignition signal No. 3
Ignition signal No. 1
Ignition signal No. 8
Ignition signal No. 6
Ignition signal No. 4
Ignition signal No. 2[Engine is running]

Warm-up condition

Idle speed
NOTE:
The pulse cycle changes depending on rpm
at idle.0 - 0.2V
[Engine is running]

Warm-up condition

Engine speed is 2,000 rpm.0.1 - 0.4V
47 YSensor power supply
(Throttle position sensor)[Ignition switch: ON]Approximately 5V TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB0050E
PBIB0051E
PBIB0044E
PBIB0045E

EC-100Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
48 SBSensor power supply
(EVAP control system pres-
sure sensor)[Ignition switch: ON]Approximately 5V
49 R/YSensor power supply
(Refrigerant pressure sen-
sor)[Ignition switch: ON]Approximately 5V
50 B Throttle position sensor 1[Ignition switch: ON]

Engine stopped

Shift lever position: D

Accelerator pedal: Fully releasedMore than 0.36V
[Ignition switch: ON]

Engine stopped

Shift lever position: D

Accelerator pedal: Fully depressedLess than 4.75V
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
55 RHeated oxygen sensor 2
(bank 1)[Engine is running]

Warm-up condition

Revving engine from idle to 3,000 rpm
quickly after the following conditions are
met.
–After keeping the engine speed between
3,500 and 4,000 rpm for 1 minute and at
idle for 1 minute under no load.0 - Approximately 1.0V
57 L/P
A/F sensor 1 (bank 2)[Engine is running]

Warm-up condition

Idle speedApproximately 2.6V
58 GR/GApproximately 2.3V
76 G/LApproximately 3.1V
77 BR/BApproximately 2.3V
66 RSensor ground
(Throttle position sensor)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
67 B Sensor ground[Engine is running]

Warm-up condition

Idle speedApproximately 0V
68 W/LSensor power supply
(Power steering pressure
sensor)[Ignition switch: ON]Approximately 5V
69 W Throttle position sensor 2[Ignition switch: ON]

Engine stopped

Shift lever position: D

Accelerator pedal: Fully releasedLess than 4.75V
[Ignition switch: ON]

Engine stopped

Shift lever position: D

Accelerator pedal: Fully depressedMore than 0.36V TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)