2004 INFINITI QX56 engine

TF-1
TRANSFER
D DRIVELINE/AXLE
CONTENTS
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Revision: August 20072004 QX56 PREPARATION ........................................................... 4
Special Service Tools ............................................... 4
Commercial Service Tools ........................................ 7
PRECAUTIONS .......................................................... 8
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” .................................................................. 8
Precautions .............................................................. 8
Service Notice .......................................................... 9
Wiring Diagrams and Trouble Diagnosis .................. 9
ALL-MODE 4WD SYSTEM ...................................... 10
Cross-sectional View .............................................. 10
Control System ........................................................11
ALL-MODE 4WD TRANSFER BASIC CONTROL
... 12
HYDRAULIC CONTROL CIRCUITS ................... 12
OUTLINE ............................................................. 12
CONTROL SYSTEM DIAGRAM ......................... 13
INDICATIONS OF 4WD WARNING LAMP ......... 13
CAN Communication .............................................. 13
SYSTEM DESCRIPTION .................................... 13
Location of Electrical Parts ..................................... 14
Description of Electrical Parts ................................ 15
TRANSFER MOTOR .......................................... 15
WAIT DETECTION SWITCH .............................. 15
2-4WD SHIFT SOLENOID VALVE ...................... 15
LINE PRESSURE SWITCH ................................ 16
Circuit Diagram for Quick Pinpoint Check .............. 17
Wiring Diagram — T/F — ....................................... 18
ON BOARD DIAGNOSTIC SYSTEM DESCRIP-
TION .......................................................................... 27
Trouble Diagnosis without CONSULT-II ................. 27
DESCRIPTION .................................................... 27
SELF-DIAGNOSTIC PROCEDURE .................... 28
INDICATIONS OF 4WD WARNING LAMP ......... 28CONSULT-II Function (ALL MODE AWD/4WD) ..... 31
Trouble Diagnosis with CONSULT-II ...................... 31
SELF-DIAGNOSIS .............................................. 31
SELF-DIAGNOSTIC ITEMS ................................ 32
DATA MONITOR ................................................. 34
DATA MONITOR ITEMS ..................................... 35
REFERENCE VALUE IN DATA MONITOR MODE
... 38
WORK SUPPORT ............................................... 41
CLUTCH FORCE RELEASE LIMIT ADJUST-
MENT .................................................................. 42
TROUBLE DIAGNOSIS — INTRODUCTION ........... 44
Introduction ............................................................. 44
DESCRIPTION .................................................... 44
DIAGNOSTIC WORKSHEET .............................. 44
Work Flow ............................................................... 46
HOW TO PERFORM TROUBLE DIAGNOSES
FOR QUICK AND ACCURATE REPAIR ............. 46
TROUBLE DIAGNOSIS — BASIC INSPECTION .... 47
Listen to Customer Complaints .............................. 47
Transfer Fluid Check .............................................. 47
Road Test ............................................................... 47
PREPARATION FOR ROAD TEST ..................... 47
1. CHECK BEFORE ENGINE IS STARTED ....... 48
2. CHECK AT IDLE .............................................. 49
3. CRUISE TEST ................................................. 53
TROUBLE DIAGNOSIS — GENERAL DESCRIP-
TION .......................................................................... 55
Transfer Control Unit Terminals and Reference
Value ....................................................................... 55
TRANSFER CONTROL UNIT HARNESS CON-
NECTOR LAYOUT .............................................. 55
TRANSFER CONTROL UNIT INSPECTION
TABLE ................................................................. 55
DTC U1000, U1001 CAN COMMUNICATION LINE ... 59
CAN Communication System Inspection ................ 59
4WD SOLENOID VALVE .......................................... 60
Diagnostic Procedure ............................................. 60
2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT

ALL-MODE 4WD SYSTEM
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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
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONPFP:00000
Trouble Diagnosis without CONSULT-IIEDS0017U
DESCRIPTION
If the engine starts when there is something wrong with the all-mode 4WD system, the 4WD warning lamp
turns ON or flickers in the combination meter. When the system functions properly, the warning lamp turns ON
when the ignition switch is turned to ON, and it turns OFF after engine starts.
To locate the cause of a problem, start the self-diagnosis function. The 4WD warning lamp in the combination
meter will indicate the problem area by flickering according to the self-diagnostic results. As for the details of
the 4WD warning lamp flickering patterns, refer to TF-28
.

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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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. —

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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CONSULT-II Function (ALL MODE AWD/4WD)EDS002G7
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
Trouble Diagnosis with CONSULT-IIEDS0017V
SELF-DIAGNOSIS
CONSULT-II Setting Procedure
1. Turn ignition switch to “OFF” position.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carry out CAN communication.
2. Connect CONSULT-II and CONSULT-II CONVERTER to data
link connector.
3. Start engine.
4. On CONSULT-II screen, touch “START (NISSAN BASED
VHCL)”.
5. Touch “ALL MODE AWD/4WD” on SELECT SYSTEM screen.
If "ALL MODE AWD/4WD" is not indicated, refer to GI-39,
"CONSULT-II Data Link Connector (DLC) Circuit" .
ALL MODE AWD/4WD diag-
nostic modeDescription
SELF-DIAG RESULTS Displays transfer control unit self-diagnosis results.
DATA MONITOR Displays transfer control unit input/output data in real time.
WORK SUPPORTSupports inspections and adjustments. Commands are transmitted to the transfer control unit for set-
ting the status suitable for required operation, input/output signals are received from the transfer con-
trol unit and received data is displayed.
CAN DIAG SUPPORT
MNTRThe results of transmit/receive diagnosis of CAN communication can be read.
ECU PART NUMBER Transfer control unit part number can be read.
BBIA0369E
BCIA0029E
BCIA0030E

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

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
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2-4WD shift solenoid valve
(2-4WD SOL)
2-4WD shift solenoid monitor
(2-4WD SOL MON)OFF
4WD shift switchIn “2WD” position
ON (“Wait” function is not oper-
ating.)
In “AUTO” position
OFF (“Wait” function is operat-
ing.)
ON (“Wait” function is not oper-
ating.)
In “4H” position
OFF (“Wait” function is operat-
ing.)
ON In “4LO” position
Battery voltage
(BATTERY VOLT)Approx. 12V Key switch “ON” and engine at rest
Approx. 13 - 14V During idling
AUTO switchOFF 4WD shift switch in other than “AUTO” position
ON 4WD shift switch in “AUTO” position
4L switchOFF 4WD shift switch in other than “4LO” position
ON 4WD shift switch in “4LO” position
N position switch
(N POSI SW AT)OFF A/T selector lever in other than “N” position
ON A/T selector lever in “N” position
R position switch
(R POSI SW AT)OFF A/T selector lever in other than “R” position
ON A/T selector lever in “R” position
P position switch
(P POSI SW AT)OFF A/T selector lever in other than “P” position
ON A/T selector lever in “P” position
Throttle opening
(THROTTLE POSI)0.0/8 - 8.0/8 Throttle fully closed (0.0/8) or throttle fully open (8.0/8) Indicated items
(Screen terms for CONSULT-II, “DATA
MONITOR” mode)Display Conditions