2006 INFINITI QX56 engine overheat

TROUBLE DIAGNOSISATC-125
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Revision: November 2009 2006 QX56
TROUBLE DIAGNOSES FOR UNUSUAL PRESSURE
Whenever system′s high and/or low side pressure is unusual, diagnose using a manifold gauge. The marker
above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the stan-
dard (usual) pressure, however, differs from vehicle to vehicle, refer to above table (Ambient air temperature-
to-operating pressure table).
Both High- and Low-pressure Sides are Too High
High-pressure Side is Too High and Low-pressure Side is Too Low
Gauge indication Refrigerant cycleProbable causeCorrective action
Both high- and low-pressure sides
are too high. Pressure is reduced soon
after water is splashed on
condenser.
Excessive refrigerant charge
in refrigeration cycle
Reduce refrigerant until speci-
fied pressure is obtained.
Air suction by cooling fan is
insufficient. Insufficient condenser cooling
performance
↓
1. Condenser fins are clogged.
2. Improper fan rotation of
cooling fan

Clean condenser.

Check and repair cooling fan
if necessary.

Low-pressure pipe is not
cold.

When compressor is
stopped high-pressure
value quickly drops by
approximately 196 kPa (2
kg/cm
2 , 28 psi). It then
decreases gradually there-
after. Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure
decreases too slowly.)
↓
Air in refrigeration cycle
Evacuate and recharge sys-
tem.
Engine tends to overheat. Engine cooling systems mal-
function. Check and repair engine cool-
ing system.

An area of the low-pres-
sure pipe is colder than
areas near the evaporator
outlet.

Plates are sometimes cov-
ered with frost.

Excessive liquid refrigerant
on low-pressure side

Excessive refrigerant dis-
charge flow

Expansion valve is open a
little compared with the
specification.
↓
Improper expansion valve
adjustment Replace expansion valve.
AC359A
Gauge indication
Refrigerant cycleProbable causeCorrective action
High-pressure side is too high and
low-pressure side is too low.
Upper side of condenser and
high-pressure side are hot,
however, liquid tank is not so
hot.High-pressure tube or parts
located between compressor
and condenser are clogged or
crushed.

Check and repair or replace
malfunctioning parts.

Check oil for contamination.
AC360A

CO-1
ENGINE COOLING SYSTEM
B ENGINE
CONTENTS
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CO
Revision: November 2009 2006 QX56
PRECAUTIONS .....................................................
..... 2
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” ............................................................. ..... 2
Precautions for Liquid Gasket ............................. ..... 2
REMOVAL OF LIQUID GASKET SEALING ..... ..... 2
LIQUID GASKET APPLICATION PROCEDURE ..... 2
PREPARATION ...................................................... ..... 4
Special Service Tools .......................................... ..... 4
Commercial Service Tools ................................... ..... 4
OVERHEATING CAUSE ANALYSIS ..................... ..... 6
Troubleshooting Chart ......................................... ..... 6
COOLING SYSTEM ............................................... ..... 8
Cooling Circuit .......................................................... 8
System Drawing ....................................................... 9
ENGINE COOLANT ............................................... ... 10
Inspection ............................................................ ... 10
LEVEL CHECK ................................................ ... 10
CHECKING COOLING SYSTEM FOR LEAKS ... 10
CHECKING RESERVOIR CAP ........................ ... 10
CHECKING RADIATOR CAP ........................... ... 10
Changing Engine Coolant ................................... ... 10
DRAINING ENGINE COOLANT ...................... .... 11
REFILLING ENGINE COOLANT ..................... .... 11
FLUSHING COOLING SYSTEM ...................... ... 12
RADIATOR ............................................................. ... 14
Removal and Installation ..................................... ... 14
REMOVAL ........................................................ ... 14
INSTALLATION ................................................ ... 16INSPECTION AFTER INSTALLATION .............
... 16
Checking Radiator ............................................... ... 16
ENGINE COOLING FAN ........................................ ... 17
Removal and Installation (Crankshaft Driven Type) ... 17
REMOVAL ........................................................ ... 17
INSPECTION AFTER REMOVAL .................... ... 17
INSTALLATION ................................................ ... 17
INSPECTION AFTER INSTALLATION ............. ... 17
Removal and Installation (Motor Driven Type) .... ... 18
REMOVAL ........................................................ ... 18
INSTALLATION ................................................ ... 18
WATER PUMP ....................................................... ... 19
Removal and Installation ..................................... ... 19
REMOVAL ........................................................ ... 19
INSPECTION AFTER REMOVAL .................... ... 19
INSTALLATION ................................................ ... 19
INSPECTION AFTER INSTALLATION ............. ... 20
THERMOSTAT AND WATER PIPING ................... ... 21
Removal and Installation ..................................... ... 21
REMOVAL ........................................................ ... 21
INSPECTION AFTER REMOVAL .................... ... 22
INSTALLATION ................................................ ... 22
INSPECTION AFTER INSTALLATION ............. ... 22
SERVICE DATA AND SPECIFICATIONS (SDS) ... ... 23
Standard and Limit ............................................... ... 23
ENGINE COOLANT CAPACITY (APPROXI-
MATE) ............................................................... ... 23
THERMOSTAT ................................................. ... 23
RADIATOR ....................................................... ... 23

CO-6Revision: November 2009
OVERHEATING CAUSE ANALYSIS
2006 QX56
OVERHEATING CAUSE ANALYSISPFP:00012
Troubleshooting ChartEBS00RE6
SymptomCheck items
Cooling sys-
tem parts
malfunction Poor heat transfer
Water pump malfunction Worn or loose drive belt
—
Thermostat stuck closed
—
Damaged fins Dust contamination or
paper clogging
Physical damage
Clogged radiator cooling
tube Excess foreign material
(rust, dirt, sand, etc.)
Water cut valve malfunction Excess foreign material
(rust, dirt, sand, etc.), phys-
ical damage
Reduced air flow Cooling fan does not oper-
ate
Fan assembly —
High resistance to fan rota-
tion
Damaged fan blades
Damaged radiator shroud —— —
Improper engine coolant
mixture ratio —— —
Poor engine coolant quality —Engine coolant density —
Insufficient engine coolant Engine coolant leaks Cooling hose
Loose clamp
Cracked hose
Water pump Poor sealing
Radiator cap Loose
Poor sealing
Radiator O-ring for damage, deterio-
ration or improper fitting
Cracked radiator tank
Cracked radiator core
Reservoir tank Cracked reservoir tank
Overflowing reservoir tank Exhaust gas leaks into
cooling systemCylinder head deterioration
Cylinder head gasket dete-
rioration

OVERHEATING CAUSE ANALYSISCO-7
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Revision: November 2009 2006 QX56
Except cool-
ing system
parts mal-
function—
Overload on engine Abusive driving
High engine rpm under no
load
Driving in low gear for
extended time
Driving at extremely high
speed
Powertrain system mal-
function
—
Installed improper size
wheels and tires
Dragging brakes
Improper ignition timing
Blocked or restricted air
flow Blocked bumper
—
—
Blocked radiator grille
Installed car brassiere
Mud contamination or
paper clogging
Blocked radiator —
Blocked condenser Blocked air flow
Installed large fog lamp
Symptom
Check items

EC-5
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EC A
Revision: November 2009 2006 QX56
Component Description .......................................
. 440
On Board Diagnosis Logic .................................. . 440
DTC Confirmation Procedure .............................. . 440
Diagnostic Procedure .......................................... . 441
Removal and Installation ..................................... . 441
DTC P0500 VSS .................................................... . 442
Description .......................................................... . 442
On Board Diagnosis Logic .................................. . 442
DTC Confirmation Procedure .............................. . 442
Overall Function Check ....................................... . 442
Diagnostic Procedure .......................................... . 443
DTC P0506 ISC SYSTEM ...................................... . 444
Description .......................................................... . 444
On Board Diagnosis Logic .................................. . 444
DTC Confirmation Procedure .............................. . 444
Diagnostic Procedure .......................................... . 445
DTC P0507 ISC SYSTEM ...................................... . 446
Description .......................................................... . 446
On Board Diagnosis Logic .................................. . 446
DTC Confirmation Procedure .............................. . 446
Diagnostic Procedure .......................................... . 447
DTC P0550 PSP SENSOR .................................... . 448
Component Description ....................................... . 448
CONSULT-II Reference Value in Data Monitor Mode . 448
On Board Diagnosis Logic .................................. . 448
DTC Confirmation Procedure .............................. . 448
Wiring Diagram ................................................... . 449
Diagnostic Procedure .......................................... . 450
Component Inspection ........................................ . 452
Removal and Installation ..................................... . 452
DTC P0603 ECM POWER SUPPLY ...................... . 453
Component Description ....................................... . 453
On Board Diagnosis Logic .................................. . 453
DTC Confirmation Procedure .............................. . 453
Wiring Diagram ................................................... . 454
Diagnostic Procedure .......................................... . 455
DTC P0605 ECM ................................................... . 457
Component Description ....................................... . 457
On Board Diagnosis Logic .................................. . 457
DTC Confirmation Procedure .............................. . 457
Diagnostic Procedure .......................................... . 458
DTC P0643 SENSOR POWER SUPPLY ............... . 460
On Board Diagnosis Logic .................................. . 460
DTC Confirmation Procedure .............................. . 460
Wiring Diagram ................................................... . 461
Diagnostic Procedure .......................................... . 463
DTC P0850 PNP SWITCH ..................................... . 465
Component Description ....................................... . 465
CONSULT-II Reference Value in Data Monitor Mode . 465
On Board Diagnosis Logic .................................. . 465
DTC Confirmation Procedure .............................. . 465
Overall Function Check ....................................... . 466
Wiring Diagram ................................................... . 467
Diagnostic Procedure .......................................... . 468
DTC P1148, P1168 CLOSED LOOP CONTROL ... . 470
On Board Diagnosis Logic .................................. . 470
DTC P1211 TCS CONTROL UNIT ........................ . 471Description ...........................................................
.471
On Board Diagnosis Logic ................................... .471
DTC Confirmation Procedure .............................. .471
Diagnostic Procedure .......................................... .471
DTC P1212 TCS COMMUNICATION LINE ........... .472
Description ........................................................... .472
On Board Diagnosis Logic ................................... .472
DTC Confirmation Procedure .............................. .472
Diagnostic Procedure .......................................... .472
DTC P1217 ENGINE OVER TEMPERATURE ....... .473
Description ........................................................... .473
CONSULT-II Reference Value in Data Monitor Mode .473
On Board Diagnosis Logic ................................... .474
Overall Function Check ....................................... .474
Wiring Diagram .................................................... .476
Diagnostic Procedure .......................................... .478
Main 12 Causes of Overheating .......................... .481
Component Inspection ......................................... .482
DTC P1225 TP SENSOR ....................................... .483
Component Description ....................................... .483
On Board Diagnosis Logic ................................... .483
DTC Confirmation Procedure .............................. .483
Diagnostic Procedure .......................................... .484
Removal and Installation ..................................... .484
DTC P1226 TP SENSOR ....................................... .485
Component Description ....................................... .485
On Board Diagnosis Logic ................................... .485
DTC Confirmation Procedure .............................. .485
Diagnostic Procedure .......................................... .486
Removal and Installation ..................................... .486
DTC P1564 ICC STEERING SWITCH ................... .487
Component Description ....................................... .487
CONSULT-II Reference Value in Data Monitor Mode .487
On Board Diagnosis Logic ................................... .487
DTC Confirmation Procedure .............................. .488
Wiring Diagram .................................................... .489
Diagnostic Procedure .......................................... .490
Component Inspection ......................................... .493
DTC P1564 ASCD STEERING SWITCH ............... .494
Component Description ....................................... .494
CONSULT-II Reference Value in Data Monitor Mode .494
On Board Diagnosis Logic ................................... .494
DTC Confirmation Procedure .............................. .495
Wiring Diagram .................................................... .496
Diagnostic Procedure .......................................... .497
Component Inspection ......................................... .500
DTC P1568 ICC FUNCTION .................................. .501
On Board Diagnosis Logic ................................... .501
DTC Confirmation Procedure .............................. .501
Diagnostic Procedure .......................................... .501
DTC P1572 ICC BRAKE SWITCH ......................... .502
Component Description ....................................... .502
CONSULT-II Reference Value in Data Monitor Mode .502
On Board Diagnosis Logic ................................... .502
DTC Confirmation Procedure .............................. .503

EC-90Revision: November 2009
TROUBLE DIAGNOSIS
2006 QX56
2
P0031 P0032 P0051 P0052 Air fuel ratio (A/F) sensor 1 heater

P0037 P0038 P0057 P0058 Heated oxygen sensor 2 heater

P0130 P0131 P0132 P0133 P0150 P0151 P0152 P0153 P2A00 P2A03 Air fuel ratio (A/F) sensor 1

P0137 P0138 P0139 P0157 P0158 P0159 Heated oxygen sensor 2

P0441 EVAP control system purge flow monitoring

P0443 P0444 P0445 EVAP canister purge volume control solenoid valve

P0447 P0448 EVAP canister vent control valve

P0451 P0452 P0453 EVAP control system pressure sensor

P0550 Power steering pressure sensor

P0603 ECM power supply

P0700 P0710 P0717 P0720 P0740 P0744 P0745 P1730 P1752 P1754 P1757 P1759 P1762 P1764 P1767 P1769
P1772 P1774 A/T related sensors and solenoid valves

P1217 Engine over temperature (OVERHEAT)

P1805 Brake switch

P2100 P2103 P2118 Electric throttle control actuator

P2101 Electric throttle control function
3

P0171 P0172 P0174 P0175 Fuel injection system function

P0300 - P0308 Misfire

P0420 P0430 Three way catalyst function

P0442 P0455 P0456 EVAP control system

P0506 P0507 Idle speed control system

P1148 P1168 Closed loop control

P1211 TCS control unit

P1212 TCS communication line

P1564 ICC/ASCD steering switch

P1568 ICC command value

P1572 ICC/ASCD brake switch

P1574 ICC/ASCD vehicle speed sensor

P2119 Electric throttle control actuator
Priority Detected items (DTC)

EC-92Revision: November 2009
TROUBLE DIAGNOSIS
2006 QX56
Symptom Matrix ChartUBS00L05
SYSTEM — BASIC ENGINE CONTROL SYSTEM
SYMPTOMRefer-
ence 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 11232 22 3 2EC-604
Fuel pressure regulator system 334444444 4 EC-82
Injector circuit11232 22 2EC-598
Evaporative emission system 334444444 4 EC-32
Air Positive crankcase ventilation sys-
tem 334444444 41
EC-45
Incorrect idle speed adjustment 1 1 1 1 1EC-71
Electric throttle control actuator 112332222 2 2 EC-528
,
EC-534
,
EC-540
,
EC-545
IgnitionIncorrect ignition timing adjustment 33111 11 1EC-71
Ignition circuit 11222 22 2EC-618
Main power supply and ground circuit 22333 33 23 EC-145
Mass air flow sensor circuit
1
12 2
222 2 EC-171,
EC-180
Engine coolant temperature sensor circuit
333
EC-192,
EC-205
Air fuel ratio (A/F) sensor 1 circuit EC-213
,
EC-223
,
EC-232
,
EC-241
,
EC-575

Throttle position sensor circuit 22EC-198
,
EC-320
,
EC-483
,
EC-485
,
EC-560
Accelerator pedal position sensor circuit 3 2 1EC-453
,
EC-547
,
EC-553
,
EC-567
Knock sensor circuit 23EC-335
Crankshaft position sensor (POS) circuit 2 2 EC-340
Camshaft position sensor (PHASE) circuit 3 2EC-347

TROUBLE DIAGNOSISEC-93
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Revision: November 2009 2006 QX56
1 - 6: The numbers refer to the order of inspection.
(continued on next page)Vehicle speed signal circuit
2 3 33EC-442
Power steering pressure sensor circuit 23 3 EC-448
ECM 22333333333 EC-453,
EC-457
Park/Neutral position (PNP) switch circuit 3 3 3 33EC-465
Refrigerant pressure sensor circuit 233 4 EC-630
Electrical load signal circuit 3EC-596
Air conditioner circuit 223333333 3 2 AT C - 3 4
ABS actuator and electric unit (control unit)4EC-471
,
EC-472

or BRC-11
SYMPTOM
Refer-
ence 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