2004 INFINITI QX56 transfer fluid

ALL-MODE 4WD SYSTEM
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Revision: August 20072004 QX56
CONTROL SYSTEM DIAGRAM
INDICATIONS OF 4WD WARNING LAMP
*: When 4WD warning lamp is ON, all the 4WD shift indicator lamps turn OFF.
CAN CommunicationEDS0017P
SYSTEM DESCRIPTION
Refer to LAN-5, "CAN COMMUNICATION" .
WDIA0075E
Condition Content 4WD warning lamp
During self-diagnosis Indicates the malfunction position by number of flickers. Flickers at malfunction mode.
Lamp check*Checks the lamp by turning ON during engine starting. After
engine starts, it turns OFF if there are no malfunctions.ON
Malfunction in 4WD system*Turns ON to indicate malfunction. When ignition switch is
turned to “OFF” or the malfunction is corrected, it turns OFF.ON
When vehicle is driven with different
diameters of front and rear tiresFlickers once every 2 seconds.
Turns OFF when ignition switch is “OFF”.Flickers once every 2 sec-
onds.
High fluid temperature in transfer unitWhen fluid temperature is high or fluid temperature sensor cir-
cuit is shorted, it flickers twice every second.
It turns OFF when fluid temperature becomes normal.Flickers twice a second.
Other than above (System is nor-
mal.)Lamp is OFF. OFF

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
TF-29
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Flickering pattern or flick-
ering conditionMalfunction Check items
2 Rear revolution sensor circuit is shorted or open.Refer to AT- 11 2 , "
DTC P0720 VEHI-
CLE SPEED SENSOR A/T (REVO-
LUTION SENSOR)" .
3 4WD solenoid valve circuit is shorted or open.Refer to TF-60, "
Diagnostic Proce-
dure" .
42-4WD shift solenoid valve circuit is shorted or 2WD switch of
4WD shift switch is shorted.Refer to TF-62, "
Diagnostic Proce-
dure" .
5 Transfer motor relay circuit is shorted or open.Refer to TF-64, "
Diagnostic Proce-
dure" .
6If unexpected signal is detected because of ABS wheel sensor
malfunction or communications error within the vehicle.Refer to BRC-38, "
Wheel Sensor
System Inspection" .
7 When malfunction in CAN communication system is detected.Refer to LAN-5, "
CAN COMMUNICA-
TION" .
8 A/D converter of transfer control unit functions improperly.Refer to EC-351, "
DTC P0605 ECM"
.
9 Transfer fluid temperature sensor circuit is open.Refer to TF-66, "
Diagnostic Proce-
dure" .
10 Neutral-4LO switch circuit is shorted or open.Refer to TF-69, "
Diagnostic Proce-
dure" .
112-4WD shift solenoid valve circuit, 2WD switch of 4WD shift
switch circuit or clutch pressure switch circuit is shorted or open.Refer to TF-62, "
Diagnostic Proce-
dure" or TF-72, "Diagnostic Proce-
dure" .
12 Line pressure switch circuit is shorted or open.Refer to TF-74, "
Diagnostic Proce-
dure" .
13 Engine speed signal circuit is shorted or open.Refer to AT- 11 5 , "
DTC P0725
ENGINE SPEED SIGNAL" .
14 Throttle position sensor circuit is shorted or open.Refer to EC-351, "
DTC P0605 ECM"
.
15 Malfunction in power supply circuit of transfer control unit. Power supply of transfer control unit
16 4WD shift switch circuit is shorted.Refer to TF-62, "
Diagnostic Proce-
dure" .
17 ABS operation signal circuit is shorted.Refer to BRC-54, "
CAN Communica-
tion System Inspection" .
18ATP switch, wait detection switch or neutral-4LO switch circuit is
shorted or open.Refer to TF-69, "
Diagnostic Proce-
dure" .
19Transfer control device actuator motor is malfunctioning. (Mal-
functions are detected when actuator motor fails to operate while
shifting from “4H” to “4LO” or vice versa.)Refer to TF-77, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Proce-
dure" .
20Transfer control device actuator motor arm position sensing
switch is malfunctioning.Refer to TF-80, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Proce-
dure" .
21Transfer control device actuator circuit is shorted or open. (Mal-
functions are detected when motor relay circuit is open/shorted or
relay monitor circuit is open/shorted.)Refer to TF-77, "
Diagnostic Proce-
dure" , TF-80, "Diagnostic Proce-
dure" or TF-82, "Diagnostic
Procedure" .
22If VDC operation signal is being input because of VDC malfunc-
tion or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
23If TCS operation signal is being input because of TCS malfunction
or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
24If unexpected signal is input because of AT PNP switch circuit or
communication error within the vehicle.Refer to AT- 1 0 9 , "
DTC P0705 PARK/
NEUTRAL POSITION SWITCH" .
Repeats flickering every
2 to 5 sec.Circuits that the self-diagnosis covers have no malfunction. —

TF-32
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
6. Touch “SELF-DIAG RESULTS” on SELECT DIAG MODE
screen.
7. Self-diagnostic results are displayed.
SELF-DIAGNOSTIC ITEMS
BCIA0031E
Detected items
(Screen terms for CONSULT-II,
“SELF-DIAG RESULT” mode)Malfunction is detected when... Check items
Revolution sensor (rear)
(VHCL SPEED SEN·RR)

Signal from vehicle speed sensor 1 (installed on A/T) is
not input due to open circuit.

Improper signal is input while driving.Refer to AT- 11 2 , "
DTC P0720
VEHICLE SPEED SENSOR A/T
(REVOLUTION SENSOR)" .
4WD solenoid valve
(DUTY SOLENOID)

Proper voltage is not applied to solenoid valve due to
open or short circuit.Refer to TF-60, "
Diagnostic Proce-
dure" .
2-4WD shift solenoid valve
(2-4WD SOLENOID)Refer to TF-62, "
Diagnostic Proce-
dure" .
Tran s fe r mo to r re lay
(MOTOR RELAY)

Motor does not operate properly due to open or short cir-
cuit in transfer motor or motor relay.Refer to TF-64, "Diagnostic Proce-
dure" .
Transfer fluid temperature sensor
(FLUID TEMP SENSOR)

Signal voltage from fluid temperature sensor is abnor-
mally high (T/F fluid temperature is abnormally low)
while driving.Refer to TF-66, "Diagnostic Proce-
dure" .
Neutral-4LO switch
(N POSI SW TF)

Improper signal is input while driving.Refer to TF-69, "Diagnostic Proce-
dure" .
Clutch pressure
(CLUTCH PRESSURE)

Improper signal is input due to open or short circuit.

Malfunction occurs in clutch pressure hydraulic circuit.(*1) Refer to TF-72, "
Diagnostic
Procedure" .
Line pressure
(LINE PRESSURE)

Improper signal is input due to open or short circuit.

Malfunction occurs in line pressure hydraulic circuit.(*1) Refer to TF-74, "
Diagnostic
Procedure" .
Engine speed signal (Note 1)
(ENGINE SPEED SIG)

Engine speed is abnormally low while driving.Refer to AT- 11 5 , "DTC P0725
ENGINE SPEED SIGNAL" .
Throttle position sensor
(THRTL POSI SEN)

Signal voltage from throttle position sensor is abnormally
high.

Signal voltage from throttle position sensor is abnormally
low when closed throttle position switch is OFF.Refer to EC-351, "
DTC P0605
ECM" .
Transfer control unit (ADC)
C/U (ADC)/THRTL SEN

Power supply voltage for A/D converter system of trans-
fer control unit is malfunctioning.Refer to EC-351, "DTC P0605
ECM" .
Battery voltage (Note 1)
(BATTERY VOLTAGE)

Power supply voltage for transfer control unit is abnor-
mally low while driving.Refer to TF-18, "Wiring Diagram —
T/F —" .
4WD shift switch
(4WD MODE SW)

More than two switch inputs are simultaneously detected
due to short circuit of 4WD shift switch.Refer to TF-62, "Diagnostic Proce-
dure" .
ABS operation signal (Note 4)
(ABS OPER SIGNAL)

When a malfunction signal due to disconnection or
shorting is detected.

When a defect signal is entered from the ABS control
unit.Refer to BRC-54, "
CAN Communi-
cation System Inspection" .
Wait detection switch (Note 2)
(WAIT DETECT SWITCH)

Improper signal is input due to open or short circuit.(*2) Refer to TF-69, "Diagnostic
Procedure" .

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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7. Touch “ECU INPUT SIGNALS” or “MAIN SIGNALS”.
8. Select “Numerical Display”, “Bar Chart Display” or “Line Graph
Display”.
9. Touch “SETTING” to set record conditions.
10. Touch “AUTO TRIG” or “MANU TRIG”.
11. Return to “SELECT MONITOR ITEM” on “DATA MONITOR”
screen and touch “START”.
12. Monitored data are displayed.
DATA MONITOR ITEMS
: Standard : Option
WDIA0084E
SAT9 7 3J
SMT963D
Item [Unit]Monitor item
Remarks ECU
INPUT
SIGNALSMAIN
SIGNALSSELEC-
TION
FROM
MENU
VHCL/SEN-FR [km/h], [MPH]Indicates average vehicle speed of ABS
front left/right wheel.
VHCL/SEN-RR [km/h], [MPH]Indicates average vehicle speed of ABS
rear left/right wheel.
Engine speed [rpm]—
Throttle position sensor—
Transfer fluid temperature sensor
[V]—
Battery voltage [V]—
2WD switch [ON-OFF] 2WD switch of 4WD shift switch
AUTO switch [ON-OFF] AUTO switch of 4WD shift switch
Lock switch [ON-OFF] 4H switch of 4WD shift switch
4L switch [ON-OFF] 4LO switch of 4WD shift switch

TF-38
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
REFERENCE VALUE IN DATA MONITOR MODE
Indicated items
(Screen terms for CONSULT-II, “DATA
MONITOR” mode)Display Conditions
Throttle position sensor
(THRTL POS SEN) 0.0/8 - 8.0/8 Throttle valve fully closed to fully open
Transfer fluid temperature sensor
(FLUID TEMP SE)Approx. 1.5 - 0.5V Transfer fluid temperature approx. 20 - 80°C (68 - 176°F)
ABS operation switch
(ABS OPER SW)OFF ABS is not operating.
ON ABS is operating.
2WD position
(2WD SWITCH)ON 4WD shift switch is in “2WD”.
OFF Except the above condition
Lock position
(LOCK SWITCH)ON 4WD shift switch is in “4H”.
OFF Except the above condition
Neutral-4LO switch
(N POSI SW TF)
AT P s w i tc h
(ATP SWITCH)
Wait detection switch
(WAIT DETCT SW)4WD shift switch position2WD,
AUTO, 4H(N) 4LO
AT P s w i t c h O F F O N O F F
Neutral-4LO switch/Wait detec-
tion switch See Note.OFF ON
Note: When shifting into or out of “4LO” the switches turn ON when “Wait” function is oper-
ating and they turn OFF when “Wait” function is canceled.
Tran s fe r mo to r re lay
(MOTOR RELAY)
Transfer motor relay monitor
(MOTOR RELAY MON)Throttle valve4WD
shift
switchA/T selector
leverMotor relay/
Motor relay
monRemarks
Fully closed2WD — OFF —
AUTO,
4LOP, N O F F
ON for approx. 2 sec. after
shifting to “P” and “N”
Others ON
4HPOFF
ON for approx. 2 sec. after
shifting to “P”
Others ON
Line pressure switch
(LINE PRES SW)OFFThe vehicle has been left at room temperature for 5 min-
utes and more with ignition switch in “OFF” position.
ONIgnition switch in “ON”, and 4WD shift switch in “AUTO” or
“4H” and A/T selector lever in “D”.
Clutch pressure switch
(CL PRES SW)OFFIgnition switch in “ON”, and 4WD shift switch in “2WD”.
(“Wait” function is not operating.)
ONIgnition switch in “ON”, and 4WD shift switch in “AUTO” or
“4H” and A/T selector lever in “D”. (“Wait” function is not
operating.)
Vehicle speed
(VHCL/S COMP)0 km/h (0 MPH) — —
Control torque
(COMP CL TORQ)0 kg-m
4WD shift switch
(“Wait” function is not oper-
ating.)In “2WD” position
39 - 1,353 N·m
(4 - 138 kg-m, 29 - 998 ft.-lb.)In “AUTO” position
1,353 N·m
(138 kg-m, 998 ft.-lb.)In “4H” or “4LO” position
4WD solenoid
(DUTY SOLENOID)4% In “2WD” position
96 - 4% In “AUTO” position
4% In “4H” or “4LO” position

TF-44
TROUBLE DIAGNOSIS — INTRODUCTION
Revision: August 20072004 QX56
TROUBLE DIAGNOSIS — INTRODUCTIONPFP:00000
IntroductionEDS0017W
DESCRIPTION
When a malfunction (indicated by the 4WD warning lamp illumination) occurs, collect information first from the
customer about how the malfunction occurs. Then, proceed with the diagnosis presuming it is the cause. Also
inspect the electrical system, paying close attention to other possibilities such as fluid level and leaks.
All-mode 4WD transfer is controlled by transfer control unit and sensors.
If a malfunction occurs in the all-mode 4WD system, the 4WD warning lamp lights up to inform of the system
malfunction. There are two ways to identify the cause of the malfunction.
1. Performing the self-diagnosis. (The 4WD warning lamp will indicate what kind of malfunction has occurred
by flickering.)
2. Performing diagnosis using CONSULT-II.
DIAGNOSTIC WORKSHEET
Information from Customer
KEY POINTS

WHAT ..... Vehicle model

WHEN..... Date, Frequencies

WHERE..... Road conditions

HOW..... Operating conditions, Symptoms
Diagnostic Worksheet
Information sheet from customer
Customer name MR/MS Model & Year VIN
Transfer model
AT X 1 4 BEngine Mileage
Incident Date Manuf. Date In Service Date
Frequency❏ Continuous ❏ Intermittent ( times a day)
Symptoms❏ 4WD shift indicator lamp does not turn on.
❏ 4WD warning lamp does not turn on.
❏ 4WD shift indicator lamp does not turn off.
❏ ATP warning lamp does not turn on.
❏ 4LO indicator lamp does not turn on.
❏ 4WD shift indicator lamp does not indicate “4H”.
❏ 4WD shift indicator lamp repeats flicking.
❏ Tight corner braking symptom occurs.
❏ 4WD system does not operate.
❏ Others.
4WD warning lamp❏ Continuously lit❏ Not lit
1.❏ Listen to customer complaints.TF-47
2.❏ Check transfer fluid.TF-47
❏ Leakage
❏ Fluid condition
❏ Fluid level
3.❏ Road testingTF-47
❏ 1. Check before engine is started.
❏ 2. Check at idle.
❏ 3. Cruise test
4.❏ Perform self-diagnosis NG items (with CONSULT-II and without CONSULT-II).TF-31
, TF-28

TROUBLE DIAGNOSIS — BASIC INSPECTION
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TROUBLE DIAGNOSIS — BASIC INSPECTIONPFP:00000
Listen to Customer ComplaintsEDS0017Y

Each customer feels differently about a problem. It is important to fully understand the symptoms or condi-
tions for a customer complaint.

Listen to the customer about how and when the malfunction occurs, and make good use of it when per-
forming the road test.
Transfer Fluid CheckEDS0017Z

Check fluid for leaks and fluid level. Refer to TF-47, "Transfer Fluid Check" .
Road TestEDS00180
PREPARATION FOR ROAD TEST

The purpose of the test is to determine overall performance of
transfer and analyze causes of problems.

When a malfunction is found in any part of transfer, perform the
road test to locate the malfunction area and repair the malfunc-
tion parts.

The road test consists of the following three parts:
1. Check before engine is started
2. Check at idle
3. Cruise test

Perform road test and place checks for NG items on the diag-
nostic worksheet. Refer to TF-44, "
Diagnostic Worksheet" .
SMT089D

TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
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30Power supply for A/D
converter &Ignition key is set to ON position. 4.5 - 5.5V
Ignition key is set to OFF position. 0V
31Transfer fluid tempera-
ture sensor &At 20°C (68°F) 1.1V
At 80°C (176°F) 0.3V
33 Transfer shift relay (High)
&While actuator is operating from “4H”
to “4LO”Battery voltage
Actuator does not operate. 0V
34 Clutch pressure switch4WD shift switch is set to AUTO or
4H, then A/T selector lever is set to D
position. (wait detection system:
OFF)Battery voltage
4WD shift switch is set to 2WD,
AUTO or 4H, then A/T selector lever
is set to D position. (wait detection
system: ON)0V
35 Line pressure switch4WD shift switch is set to 2WD,
AUTO or 4H, then A/T selector lever
is set to D position.Battery voltage
—0V
36 CONSULT-II (RX) — — —
40 ATP switch
&A/T selector lever is set to P position. Battery voltage
A/T selector lever is set to any posi-
tion other than P.Less than 1V
41Transfer motor relay
monitorTransfer motor relay is ON. Battery voltage
Transfer motor relay is OFF. Less than 1V
42Transfer shift relay
(LOW)While actuator is operating from
“4LO” to “4H” positionBattery voltage
Actuator does not operate. 0V
43 Wait detection switch4WD shift switch is set to any posi-
tion other than 4LO.Battery voltage
4WD shift switch is set to 4LO posi-
tion.*3Less than 1V
44Transfer 4LO actuator
switch4WD shift switch is set to any posi-
tion other than 4LO. (Actuator: High
position)Battery voltage
4WD shift switch is set to 4LO posi-
tion. (Actuator: Low position)Less than 1V
45 Ground — — — Te r m i n a l
No.Item ConditionJudgement standard
(Approx.)