wheel INFINITI QX4 2005 Factory Repair Manual

AUTOMATIC SPEED CONTROL DEVICE (ASCD)
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionUBS00KZC
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line
BASIC ASCD SYSTEM
Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can set vehicle speed in advance between approximately 40 km/
h (25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric throttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE indicator and SET indicator in combination meter. If any
malfunction occurs in ASCD system, it automatically deactivates control.
NOTE:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.
SET OPERATION
Press MAIN switch. (The CRUISE indicator in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press SET/COAST switch. (Then SET indicator in combination meter illuminates.)
ACCEL OPERATION
If the RESUME/ACCELERATE switch is pressed during cruise control driving, increase the vehicle speed until
the switch is released or vehicle speed reaches maximum speed controlled by the system.
And then ASCD will keep the new set speed.
CANCEL OPERATION
When any of following conditions exist, cruise operation will be canceled.

CANCEL switch is pressed

More than 2 switches at ASCD steering switch are pressed at the same time (Set speed will be cleared)

Brake pedal is depressed

Selector lever is changed to N, P, R position

Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed

VDC system is operated
When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.

Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE lamp will
stop blinking and the cruise operation will be able to work by pressing SET/COAST switch or RESUME/
ACCELERATE switch.

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
Sensor Input signal to ECM ECM function Actuator
ASCD brake switch Brake pedal operation
ASCD vehicle speed controlElectric throttle control
actuator Stop lamp switch Brake pedal operation
ASCD steering switch ASCD steering switch operation
Park/Neutral position (PNP)
switchGear position
Wheel sensor* Vehicle speed
TCM* Powertrain revolution

EC-72Revision: October 2005
BASIC SERVICE PROCEDURE
2005 QX56
BASIC SERVICE PROCEDUREPFP:00018
Basic InspectionUBS00KZU
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.
–Headlamp 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

BASIC SERVICE PROCEDURE
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Idle Mixture Ratio AdjustmentUBS00KZW
PREPARATION
1. Make sure that the following parts are in good order.

Battery

Ignition system

Engine oil and coolant levels

Fuses

ECM harness connector

Vacuum hoses

Air intake system
(Oil filler cap, oil level gauge, etc.)

Fuel pressure

Engine compression

Throttle valve

Evaporative emission system
2. On air conditioner equipped models, checks should be carried out while the air conditioner is OFF.
3. Checks should be carried out while selector lever is in P or N position.
4. When measuring CO percentage, insert probe more than 40 cm (15.7 in) into tail pipe.
5. Turn off headlamp, heater blower, rear window defogger.
6. Keep front wheels pointed straight ahead.

BASIC SERVICE PROCEDURE
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DETAILED PROCEDURE
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

BASIC SERVICE PROCEDURE
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OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume LearningUBS00L00
DESCRIPTION
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific
range. It must be performed under any of the following conditions:

Each time electric throttle control actuator or ECM is replaced.

Idle speed or ignition timing is out of specification.
PREPARATION
Before performing Idle Air Volume Learning, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.

Battery voltage: More than 12.9V (At idle)

Engine coolant temperature: 70 - 100°C (158 - 212°F)

Park/Neutral position (PNP) switch: ON

Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, if the parking brake is applied before the engine
is start the headlamp will not be illuminated.

Steering wheel: Neutral (Straight-ahead position)

Vehicle speed: Stopped

Transmission: Warmed-up
For models with CONSULT-II, drive vehicle until “ATF TEMP SE 1” in “DATA MONITOR” mode of “A/T”
system indicates less than 0.9V.
For models without CONSULT-II, drive vehicle for 10 minutes.
OPERATION PROCEDURE
With CONSULT-II
1. Perform EC-90, "Accelerator Pedal Released Position Learning" .
2. Perform EC-90, "
Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Select “IDLE AIR VOL LEARN” in “WORK SUPPORT” mode.
SEF 2 17 Z

EC-118Revision: October 2005
TROUBLE DIAGNOSIS
2005 QX56
3LThrottle control motor relay
power supply[Ignition switch: ON]BATTERY VOLTAGE
(11 - 14V)
4 L/W Throttle control motor (Close)[Ignition switch: ON]

Engine: Stopped

Selector lever: D

Accelerator pedal: Fully released0 - 14V
5 L/B Throttle control motor (Open)[Ignition switch: ON]

Engine: Stopped

Selector lever: D

Accelerator pedal: Fully depressed0 - 14V
6GRHeated oxygen sensor 2
heater (bank 1)[Engine is running]

Warm-up condition

Engine speed is below 3,600 rpm after the
following conditions are met.
–Keeping the engine speed between 3,500
and 4,000 rpm for 1 minute and at idle for 1
minute under no load0 - 1.0V
[Ignition switch: ON]

Engine: Stopped
[Engine is running]

Engine speed: Above 3,600 rpmBATTERY VOLTAGE
(11 - 14V)
12 RPower steering pressure sen-
sor[Engine is running]

Steering wheel: Being turned0.5 - 4.5V
[Engine is running]

Steering wheel: Not being turned0.4 - 0.8V
13 OCrankshaft position sensor
(POS)[Engine is running]

Warm-up condition

Idle speed
NOTE:
The pulse cycle changes depending on rpm
at idleApproximately 10V
[Engine is running]

Engine speed: 2,000 rpmApproximately 10V TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB1104E
PBIB1105E
PBIB1041E
PBIB1042E

TROUBLE DIAGNOSIS
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ENGINE CONTROL COMPONENT PARTS/CONTROL SYSTEMS APPLICATION
ItemDIAGNOSTIC TEST MODE
WORK
SUP-
PORTSELF-DIAGNOSTIC
RESULTS
DATA
MONI-
TORDATA
MONI-
TOR
(SPEC)ACTIVE
TESTDTC & SRT
CONFIRMATION
DTC*1FREEZE
FRAME
DATA*2SRT
STATUSDTC
WORK
SUP-
PORT
ENGINE CONTROL COMPONENT PARTS
INPUT
Crankshaft position sensor (POS)××××
Camshaft position sensor (PHASE)××××
Mass air flow sensor×××
Engine coolant temperature sensor×××××
Air fuel ratio (A/F) sensor 1×××××
Heated oxygen sensor 2×××××
Wheel sensor××××
Accelerator pedal position sensor×××
Throttle position sensor××××
Fuel tank temperature sensor××××
EVAP control system pressure
sensor×××
Intake air temperature sensor××××
Knock sensor×
Refrigerant pressure sensor××
Closed throttle position switch
(accelerator pedal position sensor
signal)××
Air conditioner switch××
Park/neutral position (PNP) switch×××
St o p l a m p s w it c h×××
Power steering pressure sensor×××
Battery voltage××
Load signal××
Fuel level sensor×××
ICC steering switch×××
ASCD steering switch×××
ICC brake switch×××
ASCD brake switch×××

TROUBLE DIAGNOSIS
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CONSULT-II Reference Value in Data MonitorUBS00L0D
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 in
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 CONSULT-II value with the tachometer indica-
tion.Almost the same speed as the
tachometer indication.
MAS A/F SE-B1 See EC-146, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
B/FUEL SCHDL See EC-146, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
A/F ALPHA-B1
A/F ALPHA-B2See EC-146, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
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
rpmFluctuates around 1.5 V
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 loadRevving engine from idle to 3,000 rpm
quickly0 - 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
VHCL SPEED SE

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

Ignition switch: ON (Engine stopped) 11 - 14V
ACCEL SEN 1

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
ACCEL SEN 2*

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
THRTL SEN 1
THRTL SEN 2*

Ignition switch: ON
(Engine stopped)

Selector 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: ONSelector lever: P or N ON
Selector lever: Except above OFF
PW/ST SIGNAL

Engine: After warming up, idle
the engineSteering wheel: Not being turned
(Forward direction)OFF
Steering wheel: Being 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

EC-142Revision: October 2005
TROUBLE DIAGNOSIS
2005 QX56
IGNITION SW
Ignition switch: ON → OFF → ON ON → OFF → ON
HEATER FAN SW

Engine: After warming up, idle
the engineHeater fan: Not operating OFF
Heater fan: Operating ON
BRAKE SW

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

Engine: After warming up

Selector lever: P or N

Air conditioner switch: OFF

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

Engine: After warming up

Selector lever: P or N

Air conditioner switch: OFF

No loadIdle 10° - 20° BTDC
2,000 rpm 25° - 45° BTDC
CAL/LD VALUE

Engine: After warming up

Selector lever: P or N

Air conditioner switch: OFF

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

Engine: After warming up

Selector lever: P or N

Air conditioner switch: OFF

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

Selector lever: P or N

Air conditioner switch: OFF

No loadIdle
(Accelerator pedal: Not depressed
even slightly, after engine starting.)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: 99°C
(210°F) or lessOFF
Engine coolant temperature: 100°C
(212°F) or moreHI
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 CONSULT-II value with the 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 mile) MONITOR ITEM CONDITION SPECIFICATION

TROUBLE DIAGNOSIS
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*: 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.A/F S1 HTR (B1)
A/F S1 HTR (B2)

Engine: After warming up, idle the engine 0 - 100%
AC PRESS SEN

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

Engine: Idle

Air conditioner switch: ON1.0 - 4.0V
VHCL SPEED SE

Turn drive wheels and compare CONSULT-II value with the 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: ONMAIN switch: Pressed ON
MAIN switch: Released OFF
CANCEL SW

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

Ignition switch: ONRESUME/ACCELERATE switch:
PressedON
RESUME/ACCELERATE switch:
ReleasedOFF
SET SW

Ignition switch: ONSET/COAST switch: Pressed ON
SET/COAST 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: ONMAIN switch: Pressed at the 1st time
→ at the 2nd timeON → OFF
SET LAMP

MAIN switch: ON

Vehicle speed: Between 40 km/h
(25 MPH) and 144 km/h (89
MPH)ASCD: Operating ON
ASCD: Not operating OFF MONITOR ITEM CONDITION SPECIFICATION