2004 INFINITI QX56 matic j

DTC P1564 ASCD STEERING SWITCH
EC-517
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Revision: August 20072004 QX56
DTC P1564 ASCD STEERING SWITCHPFP:25551
Component DescriptionUBS00HB8
ASCD steering switch has variant values of electrical resistance for
each button. ECM reads voltage variation of switch, and determines
which button is operated.
Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE
(ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HB9
Specification data are reference values.
On Board Diagnosis LogicUBS00HBA
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:
If DTC P1564 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer to
EC-351, "
DTC P0605 ECM" .
BBIA0362E
MONITOR ITEM CONDITION SPECIFICATION
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
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1564
1564ASCD steering switch

An excessively high voltage signal from the
ASCD steering switch is sent to ECM.

ECM detects that input signal from the ASCD
steering switch is out of the specified range.

ECM detects that the ASCD steering switch is
stuck ON.

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

ASCD steering switch

ECM

EC-534Revision: August 2007
DTC P1572 ASCD BRAKE SWITCH
2004 QX56
DTC P1572 ASCD BRAKE SWITCHPFP:25320
Component DescriptionUBS00HBF
When the brake pedal is depressed, ASCD brake switch is turned
OFF and stop lamp switch is turned ON. ECM detects the state of
the brake pedal by this input of two kinds (ON/OFF signal).
Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE
(ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HBG
Specification data are reference values.
On Board Diagnosis LogicUBS00HBH
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:
If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer to
EC-351, "
DTC P0605 ECM"
BBIA0373E
MONITOR ITEM CONDITION SPECIFICATION
BRAKE SW 1
(ASCD brake switch)

Ignition switch: ON
Brake pedal: Fully released ON

Brake pedal: Slightly depressed OFF
BRAKE SW 2
(stop lamp switch)

Ignition switch: ON
Brake pedal: Fully released OFF

Brake pedal: Slightly depressed ON
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1572
1572ASCD brake switchWhen the vehicle speed is above 30 km/h
(19 MPH), ON signals from the stop lamp
switch and the ASCD brake switch are sent
to the ECM at the same time.

Harness or connectors
(The stop lamp switch circuit is open or
shorted.)

Harness or connectors
(The ASCD brake switch circuit is open or
shorted.)

Stop lamp switch

ASCD brake switch

Incorrect stop lamp switch installation

Incorrect ASCD brake switch installation

ECM

EC-544Revision: August 2007
DTC P1574 ASCD VEHICLE SPEED SENSOR
2004 QX56
DTC P1574 ASCD VEHICLE SPEED SENSORPFP:31036
Component DescriptionUBS00HBM
The ECM receives two vehicle speed sensor signals via CAN communication line. One is sent from combina-
tion meter and the other is from TCM (Transmission control module). The ECM uses these signals for ASCD
control. Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE (ASCD)" for ASCD functions.
On Board Diagnosis LogicUBS00HBN
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:

If DTC P1574 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .

If DTC P1574 is displayed with DTC P0500, first perform the trouble diagnosis for DTC P0500.
Refer to EC-340, "
DTC P0500 VSS".

If DTC P1574 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605.
Refer to EC-351, "
DTC P0605 ECM".
DTC Confirmation ProcedureUBS00HBO
CAUTION:
Always drive vehicle at a safe speed.
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.
TESTING CONDITION:
Step 3 may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road test
is expected to be easier, it is unnecessary to lift the vehicle.
WITH CONSULT-II
1. Start engine (VDC switch OFF).
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Drive the vehicle at more than 40 km/h (25 MPH).
4. If DTC is detected, go to EC-545, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
DTC No.Trouble Diagnosis
NameDTC Detecting Condition Possible Cause
P1574
1574ASCD vehicle speed
sensorECM detects a difference between two vehicle
speed signals is out of the specified range.

Harness or connectors
(The CAN communication line is open or
shorted.)

Combination meter

ABS actuator and electric unit (control unit)

Wheel sensor

TCM

ECM
SEF 0 58 Y

ASCD BRAKE SWITCH
EC-621
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Revision: August 20072004 QX56
ASCD BRAKE SWITCHPFP:25320
Component DescriptionUBS00HDO
When the brake pedal is depressed, ASCD brake switch is turned
OFF and stop lamp switch is turned ON. ECM detects the state of
the brake pedal by this input of two kinds (ON/OFF signal).
Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE
(ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HDP
Specification data are reference values.
BBIA0373E
MONITOR ITEM CONDITION SPECIFICATION
BRAKE SW 1
(ASCD brake switch)

Ignition switch: ON
Brake pedal: Fully released ON

Brake pedal: Slightly depressed OFF
BRAKE SW 2
(stop lamp switch)

Ignition switch: ON
Brake pedal: Fully released OFF

Brake pedal: Slightly depressed ON

EC-628Revision: August 2007
ASCD INDICATOR
2004 QX56
ASCD INDICATORPFP:24814
Component DescriptionUBS00HDT
ASCD indicator lamp illuminates to indicate ASCD operation status. Lamp has two indicators, CRUISE and
SET, and is integrated in combination meter.
CRUISE indicator illuminates when ON/OFF switch on ASCD steering switch is turned ON to indicated that
ASCD system is ready for operation.
SET indicator illuminates when following conditions are met.

CRUISE indicator is illuminated.

SET switch on ASCD steering switch is turned ON while vehicle speed is within the range of ASCD set-
ting.
SET indicator remains lit during ASCD control.
Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE (ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HDU
Specification data are reference value.
MONITOR ITEM CONDITION SPECIFICATION
CRUISE LAMP

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

ON/OFF switch: ON

When vehicle speed is
between 40 km/h (25 MPH)
and 144 km/h (89 MPH)

COAST/SET switch: Pressed ON

COAST/SET switch: Released OFF

EC-640Revision: August 2007
ON BOARD REFUELING VAPOR RECOVERY (ORVR)
2004 QX56
ON BOARD REFUELING VAPOR RECOVERY (ORVR)PFP:00032
System DescriptionUBS00HE2
From the beginning of refueling, the air and vapor inside the fuel tank go through refueling EVAP vapor cut
valve and EVAP/ORVR line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is
released to the atmosphere.
When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and
refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged
during driving.
WAR NIN G:
When conducting inspections below, be sure to observe the following:

Put a “CAUTION: INFLAMMABLE” sign in workshop.

Do not smoke while servicing fuel system. Keep open flames and sparks away from work area.

Be sure to furnish the workshop with a CO2 fire extinguisher.
CAUTION:

Before removing fuel line parts, carry out the following procedures:
–Put drained fuel in an explosion-proof container and put lid on securely.
–Release fuel pressure from fuel line. Refer to EC-46, "FUEL PRESSURE RELEASE" .
–Disconnect battery ground cable.

Always replace O-ring when the fuel gauge retainer is removed.

Do not kink or twist hose and tube when they are installed.

Do not tighten hose and clamps excessively to avoid damaging hoses.

After installation, run engine and check for fuel leaks at connection.

Do not attempt to top off the fuel tank after the fuel pump nozzle shuts off automatically.
Continued refueling may cause fuel overflow, resulting in fuel spray and possibly a fire.
PBIB1068E

AUTOMATIC SPEED CONTROL DEVICE (ASCD)
EC-647
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Revision: August 20072004 QX56
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionUBS00HE7
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 pressing 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.
SET OPERATION
Press ON/OFF(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 COAST/SET switch. (Then SET indicator in combination meter illuminates.)
ACCEL OPERATION
If the ACCEL/RESUME 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/TCS 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 COAST/SET switch or ACCEL/
RESUME switch.

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If ON/OFF(MAIN) switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled
and vehicle speed memory will be erased.
COAST OPERATION
When the COAST/SET switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.
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
Combination meter* Vehicle speed
TCM* Powertrain revolution

EC-648Revision: August 2007
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
2004 QX56
RESUME OPERATION
When the ACCEL/RESUME switch is pressed after cancel operation other than pressing ON/OFF(MAIN)
switch is performed, vehicle speed will return to last set speed. To resume vehicle set speed, vehicle condition
must meet following conditions.

Brake pedal is released

A/T selector lever is in other than P and N positions

Vehicle speed is greater than 40 km/h (25 MPH) and less than 144 km/h (89 MPH)
Component DescriptionUBS00HE8
ASCD STEERING SWITCH
Refer to EC-517 .
ASCD BRAKE SWITCH
Refer to EC-534 , and EC-621 .
STOP LAMP SWITCH
Refer to EC-534 , EC-551 and EC-621 .
ELECTRIC THROTTLE CONTROL ACTUATOR
Refer to EC-365 , EC-367 , EC-373 and EC-378 .
ASCD INDICATOR
Refer to EC-628 .