2004 INFINITI QX56 ECU

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
TF-35
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Revision: August 20072004 QX56
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-36
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Revision: August 20072004 QX56
N position switch TF [ON-OFF] N position switch of transfer
Line pressure switch [ON-OFF] Line pressure switch
Clutch pressure switch [ON-OFF] Clutch pressure switch
ATP switch [ON-OFF]—
N position switch AT [ON-OFF] “N” position on A/T PNP switch
R position switch AT [ON-OFF] “R” position on A/T PNP switch
P position switch AT [ON-OFF] “P” position on A/T PNP switch
ABS operation switch [ON-OFF] ABS operation switch
Wait detection switch [ON-OFF] —
Throttle positionThrottle opening recognized by transfer
control unit
4WD-mode4WD-mode recognized by transfer control
unit (2WD, AUTO, 4H & 4LO)
Vehicle speed comp [km/h (MPH)]Vehicle speed recognized by transfer con-
trol unit
*Control torque [N·m (kg-m, ft.-lb.)]Calculated torque recognized by transfer
control unit
Duty solenoid valve [%]
(Transfer 4WD solenoid valve)—
2-4WD shift solenoid valve [ON-
OFF]
Control signal outputs of transfer control
unit Transfer motor relay [ON-OFF]
Shift activating 1 [ON-OFF]
Shift activating 2 [ON-OFF]
2-4WD shift solenoid valve monitor
[ON-OFF]
Check signal (re-input signal) of transfer
control unit control signal output is dis-
played. If circuit is shorted or open, ON/OFF
state does not change. Transfer motor relay monitor [ON-
OFF]
Shift activating monitor 1 [ON-OFF]
Shift activating monitor 2 [ON-OFF]
4WD fail lamp [ON-OFF]Transfer control unit control signal output for
4WD warning lamp (left)
Shift position switch 1 [ON-OFF] —
Shift position switch 2 [ON-OFF] —
2WD indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (rear)
AUTO indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (front & rear)
LOCK indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (center)
4LO indicator lamp [ON-OFF]Transfer control unit control signal output for
4WD shift indicator lamp (right) Item [Unit]Monitor item
Remarks ECU
INPUT
SIGNALSMAIN
SIGNALSSELEC-
TION
FROM
MENU

ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
TF-37
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Revision: August 20072004 QX56
*: This item is indicated as “COMP CL TORQ”.Clutch limit [N·m (kg-m, ft.-lb.)]Clutch force release limit value set in
WORK SUPPORT
Voltage [V]Value measured by voltage probe is dis-
played.
Frequency [Hz]Value measured by pulse probe is dis-
played. If measurement is impossible, “#”
sign is displayed. “#” sign is also displayed
at the final data value until the measure-
ment result is obtained.
DUTY-HI
Duty cycle value for measurement probe is
displayed.
DUTY-LOW
PLS WIDTH-HI
Measured pulse width of measurement
probe is displayed.
PLS WIDTH-LOW
FR/RR G-SEN [G] Displayed, but do not use.
TF F SPEED [km/h], [MPH] Displayed, but do not use.
AT R SPEED [km/h], [MPH] Indicates A/T rear vehicle speed.
A/T actual gear position Indicates A/T actual gear position.
VDC OPER SW [ON-OFF] Indicates VDC operation switch.
TCS OPER SW [ON-OFF] Indicates TCS operation switch.
AT P L A M P [O N - O F F ]Indicates C/U control signal output of ATP
lamp. Item [Unit]Monitor item
Remarks ECU
INPUT
SIGNALSMAIN
SIGNALSSELEC-
TION
FROM
MENU

TF-62
2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCH
Revision: August 20072004 QX56
2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCHPFP:00000
Diagnostic ProcedureEDS00184
1. CHECK 2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCH
Refer to TF-95, "
2-4WD SHIFT SOLENOID VALVE AND TRANS-
FER FLUID TEMPERATURE SENSOR" and TF-95, "4WD SHIFT
SWITCH" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace 2-4WD shift solenoid valve or 4WD
shift switch.
2. CHECK INPUT SIGNAL
With CONSULT-II
1. Select “ECU INPUT SIGNALS” in Data Monitor.
2. Read out ON/OFF status of “2WD SW” and “LOCK SWITCH”.
OK or NG
OK >> 1. Perform transfer control unit input/output signal
inspection. Refer to TF-55, "
TRANSFER CONTROL
UNIT INSPECTION TABLE" .
2. If NG, recheck transfer control unit pin terminals for
damage or loose connection with harness connector.
NG >> GO TO 3.
SMT778D
SMT974D

TRANSFER FLUID TEMPERATURE SENSOR
TF-67
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Revision: August 20072004 QX56
3. CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in Data Monitor.
3. Read out the value of “FLUID TEMP SE”.
OK or NG
OK >> GO TO 5.
NG >> Check the following.

Continuity between transfer control unit and transfer terminal cord assembly harness connectorVo l ta g e
20°C (68°F) : Approx. 1.1V
80°C (176°F) : Approx. 0.3V
SMT784D
SMT974D

CLUTCH PRESSURE SWITCH
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Revision: August 20072004 QX56
5. CHECK INPUT SIGNAL
With CONSULT-II
1. Turn ignition switch to ON position.
2. Select “ECU INPUT SIGNALS” in Data Monitor.
3. Put A/T selecor lever in D.
4. Turn 4WD shift switch to 4H and back to 2WD while reading out
ON/OFF status of "CL PRES SW".
OK or NG
OK >> GO TO 7.
NG >> Check the following.

Continuity between transfer control unit and transfer
terminal cord assembly harness connector

Clutch pressure switch.
Refer to TF-95, "
4WD SOLENOID VALVE, CLUTCH
PRESSURE SWITCH AND LINE PRESSURE
SWITCH" .
6. CHECK INPUT SIGNAL
Without CONSULT-II
1. Turn ignition switch to ON position and set 4WD shift switch to
4H position.
2. Check voltage between transfer control unit harness connector
E143 terminal 34 (BR) and ground. Refer to TF-55, "
Transfer
Control Unit Terminals and Reference Value"
OK or NG
OK >> GO TO 7.
NG >> Check the following.

Continuity between transfer control unit and transfer
terminal cord assembly harness connector

Clutch pressure switch.
Refer to TF-95, "
4WD SOLENOID VALVE, CLUTCH PRESSURE SWITCH AND LINE PRES-
SURE SWITCH" .
7. PERFORM SELF-DIAGNOSIS AGAIN
1. Check hydraulic parts.
2. After driving for a while, perform self-diagnosis again. Refer to TF-27, "
Trouble Diagnosis without CON-
SULT-II" .
OK or NG
OK >> Inspection End.
NG >> 1. Perform transfer control unit input/output signal inspection. Refer to TF-55, "
TRANSFER CON-
TROL UNIT INSPECTION TABLE" .
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with harness
connector.
SMT788D
WDIA0087E
LDIA0075E

TF-74
LINE PRESSURE SWITCH
Revision: August 20072004 QX56
LINE PRESSURE SWITCHPFP:00000
Diagnostic ProcedureEDS00189
1. CHECK MALFUNCTION
Is this malfunction detected only while driving in reverse?
Ye s o r N o
Yes >> Check A/T PNP switch “R” position.

Refer to AT-109, "DTC P0705 PARK/NEUTRAL POSITION SWITCH" .
No >> GO TO 2.
2. CHECK OTHER MALFUNCTIONS
Are other malfunctions also detected by self-diagnosis and CONSULT-II?
Refer to TF-27, "
Trouble Diagnosis without CONSULT-II" and TF-31, "Trouble Diagnosis with CONSULT-II" .
Ye s o r N o
Yes >> Check for other malfunctions.

(When other malfunctions are eliminated, line pressure switch malfunction display may disap-
pear.)
No >> GO TO 3.
3. CHECK INPUT SIGNAL
Do you have CONSULT-II?
Ye s o r N O
Yes >> GO TO 4.
No >> GO TO 5.
4. CHECK INPUT SIGNAL
With CONSULT-II
1. Select “ECU INPUT SIGNALS” in Data Monitor.
2. Put A/T selector lever in D.
3. Turn the 4WD shift switch to 4H and back to 2WD while reading
out ON/OFF status of "LINE PRES SW".
OK or NG
OK >> GO TO 6.
NG >> Check the following.

Continuity between transfer control unit and transfer
terminal cord assembly harness connector

Line pressure switch
Refer to TF-95, "
4WD SOLENOID VALVE, CLUTCH
PRESSURE SWITCH AND LINE PRESSURE
SWITCH" .
SMT790D
WDIA0087E

TROUBLE DIAGNOSES FOR SYMPTOMS
TF-93
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Revision: August 20072004 QX56
Symptom 8. Tight Corner Braking Symptom (Tight Corner Braking Symptom
Occurs-Hydraulic System Failure)
EDS0018L
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Select “ECU INPUT SIGNALS” in Data Monitor.
2. Put A/T selector lever in D.
3. Turn 4WD shift switch to 4H and back to 2WD while reading out
ON/OFF status of "CL PRES SW".
Without CONSULT-II
Check voltage between transfer control unit harness connector E143
terminal 34 (BR) and ground.
Refer to TF-55, "
TRANSFER CONTROL UNIT INSPECTION
TABLE" .
OK or NG
OK >> Disassemble transfer unit and check the following.

Control valve assembly

4WD solenoid valve

2-4WD shift solenoid valve

Clutch piston

Clutch assembly
NG >> GO TO 2.
2. CHECK CLUTCH PRESSURE SWITCH CIRCUIT
Check clutch pressure switch circuit.
Refer to TF-72, "
Diagnostic Procedure" .
OK or NG
OK >> GO TO 3.
NG >> Check, repair or replace faulty parts.
3. CHECK PROCEDURES FROM THE BEGINNING AGAIN
Check again.
OK or NG
OK >> Inspection End.
NG >> Recheck each connector pin terminals for damage or loose connection.
WDIA0087E