2004 INFINITI QX56 relay

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
TF-33
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Revision: August 20072004 QX56
Note 1: When a malfunction occurs, it is only displayed and not stored in the memory.
Note 2: When the wait detection switch has been properly fixed, malfunction information is erased from the memory.
Note 3: If 4WD shift switch is left between 4H and 4LO for a while, this indication may be displayed.
(*1): If the malfunction is detected only while driving in reverse, check the continuity of “R” position on A/T PNP switch. When there is
nothing wrong with the electrical system, check the hydraulic system.
(*2): If a revolution sensor malfunction is detected at the same time, check the revolution sensor circuit first.
Note 4: When this malfunction is detected with the ABS warning lamp off, first check for disconnection or shorting in the harness
between the transfer control unit and the ABS control unit.
Note 5: When several systems including CAN communication system indicate malfunctions, perform diagnosis of the CAN communica-
tion first.Shift actuator abnormal
(SHIFT ACT)Transfer control device actuator motor is malfunctioning.
(Malfunctions 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 Pro-
cedure" .
Shift actuator position switch
abnormal
(SHIFT ACT P/S)Transfer control device actuator motor arm position sens-
ing switch is malfunctioning.Refer to TF-80, "
Diagnostic Proce-
dure" or TF-82, "Diagnostic Pro-
cedure" .
Shift actuator circuit abnormal
(SHIFT ACT CIR)Transfer control device actuator circuit is shorted or open.
(Malfunctions 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"TF-82, "Diagnostic
Procedure" .
Memory power supply stop

Due to removal of battery which cuts off power supply to
transfer control unit, self-diagnosis memory function is
suspended.Refer to TF-76, "Diagnostic Proce-
dure" .
Transfer control unit (RAM)
[CONTROL UNIT (RAM)]

Malfunction is detected in the memory (RAM) system of
transfer control unit.—
Transfer control unit (ROM)
[CONTROL UNIT (ROM)]

Malfunction is detected in the memory (ROM) system of
transfer control unit.—
Transfer control unit (EEPROM)
[CONTROL UNIT (EEPROM)]

Malfunction is detected in the memory (EEPROM) sys-
tem of transfer control unit.—
Longitudinal G-sensor Displayed, but do not use. —
ABS VHL SPD SEN

ABS vehicle speed sensor signal is not input due to an
open circuit.

An unexpected signal is input when vehicle is being
driven.Refer to ABS vehicle speed sensor
diagnosis.
STEERING ANGLE SENSOR Displayed, but do not use. —
VDC OPER SIGIf VDC operation signal is being input because of VDC
malfunction or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
TCS OPER SIGIf TCS operation signal is being input because of TCS mal-
function or communication error within the vehicle.Refer to BRC-40, "
ABS/TCS/VDC
Control Unit Inspection" .
CAN COMM (Note 5) Malfunction is detected in CAN communication.Refer to LAN-5, "
CAN COMMUNI-
CATION" .
A/T POSITION SIGNALWhen AT PNP switch circuit is malfunction or communica-
tion error between the vehiclesRefer to AT-109, "
DTC P0705
PARK/NEUTRAL POSITION
SWITCH" . Detected items
(Screen terms for CONSULT-II,
“SELF-DIAG RESULT” mode)Malfunction is detected when... Check items

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

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

TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
TF-55
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Revision: August 20072004 QX56
TROUBLE DIAGNOSIS — GENERAL DESCRIPTIONPFP:00000
Transfer Control Unit Terminals and Reference ValueEDS00181
TRANSFER CONTROL UNIT HARNESS CONNECTOR LAYOUT
TRANSFER CONTROL UNIT INSPECTION TABLE
LDIA0066E
Te r m i n a l
No.Item ConditionJudgement standard
(Approx.)
12-4WD shift solenoid
valve &4WD shift switch is set to 2WD posi-
tion.Less than 1V
4WD shift switch is set to any posi-
tion other than 2WD.Battery voltage
24WD shift indicator lamp
(2WD)Lamp lights while system is operating
properly.Less than 1V
&2WD indicator lamp does not come
on.Battery voltage
3Ground — —
4 Transfer shift relay (High)While actuator is operating (4H →
4LO)Battery voltage
Actuator does not operate. Less than 1V
5 4WD warning lampLamp comes ON (when engine is
stopped).
(Fail-safe condition appears on dis-
play, engine is stopped, actuator
position detection switch is inopera-
tive, oil temperature is too high and/
or tires of different size are installed.)Less than 1V
Except above Battery voltage
6Ground — — —
7CAN-H — — —
8CAN-L — — —
9 4WD shift switch (2WD)
&4WD shift switch is set to 2WD posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than 2WD.Less than 1V
10 Transfer dropping resistor4WD shift switch is set to AUTO posi-
tion.4 - 14V
4WD shift switch is set to any posi-
tion other than 2WD.Less than 1V

TF-56
TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
Revision: August 20072004 QX56
114WD shift indicator lamp
(4H)“4H” indicator lamp comes ON. Less than 1V
4WD shift switch is set to any posi-
tion other than 4H.Battery voltage
124WD shift indicator lamp
(4LO)“4LO” indicator lamp comes ON. 0V
4WD shift switch is set to any posi-
tion other than 4LO.Battery voltage
13 Transfer shift relay (Low)
&While actuator is operating (4LO →
4H)Battery voltage
Actuator does not operate. 0V
14 Transfer motor relayTransfer motor relay is ON. Battery voltage
Transfer motor relay is OFF. Less than 1V
15 ATP lampAT selector lever is set to P position. Battery voltage
AT selector lever is set to any posi-
tion other than P.0V
16 Power supply —Ignition key is set to ON position. Battery voltage
Ignition key is set to OFF position. 0V
18 4WD shift switch (4H)
&4WD shift switch is set to 4H posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than 4H.Less than 1V
19 4WD solenoid valve4WD shift switch is set to AUTO posi-
tion.1.5 - 3V
4WD shift switch is set to any posi-
tion other than 2WD.Less than 1V
214WD shift indicator lamp
(AUTO)“AUTO” indicator lamp comes ON. 0V
4WD shift switch is set to any posi-
tion other than AUTO.Battery voltage
22 Power supply —Ignition key is set to ON position. Battery voltage
Ignition key is set to OFF position. 0V
23 4WD shift switch (4LO)
&4WD shift switch is set to 4LO posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than 4LO.Less than 1V
24 4WD shift switch (AUTO)4WD shift switch is set to AUTO posi-
tion.Battery voltage
4WD shift switch is set to any posi-
tion other than AUTO.Less than 1V
25 Neutral-4LO switchTransfer is set to 4LO position. 0V
Transfer is set to any position other
than 4LO.Battery voltage
27Transfer 4H actuator
switch4WD shift switch is set to 4H posi-
tion.Less than 1V
4WD shift switch is set to any posi-
tion other than 4H.Battery voltage
28 Sensor ground — Less than 1V Te r m i n a l
No.Item ConditionJudgement standard
(Approx.)

TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
TF-57
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Revision: August 20072004 QX56
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.)

TF-64
TRANSFER MOTOR AND TRANSFER MOTOR RELAY
Revision: August 20072004 QX56
TRANSFER MOTOR AND TRANSFER MOTOR RELAYPFP:00000
Diagnostic ProcedureEDS00185
1. CHECK TRANSFER MOTOR AND TRANSFER MOTOR RELAY
Refer to TF-96, "
TRANSFER MOTOR" and TF-97, "TRANSFER
MOTOR RELAY" .
OK or NG
OK >> GO TO 2.
NG >> Replace transfer motor or transfer motor relay.
2. CHECK INPUT SIGNAL
With CONSULT-II
1. Select “MAIN SIGNALS” in Data Monitor.
2. Read out ON/OFF status of “MOTOR RELAY”.
3. When the value is different from standard value although ON/
OFF switching occurs, check the following items.

PNP switch and throttle position sensor circuits
Refer to AT-109, "
DTC P0705 PARK/NEUTRAL POSITION
SWITCH" , AT-129, "DTC P1705 THROTTLE POSITION SEN-
SOR" .
OK or NG
OK >> GO TO 3.
NG >> 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.
3. CHECK TRANSFER MOTOR RELAY POWER SOURCE
1. Disconnect transfer motor relay harness connectors E153 and
E154.
2. Turn ignition switch to ON position.
3. Check voltage between transfer motor relay harness connector
E153 terminal 5 (G/R), E154 terminal 2 (Y/R), and ground.
OK or NG
OK >> GO TO 4.
NG >> Check the following.

No. 58 fuse (20A)

No. 49 fuse (10A)

Harness continuity between ignition switch and No. 58 fuse (20A) and No. 49 fuse (10A).

Harness continuity between fuse and transfer motor relay.
LDIA0102E
SMT975D
Voltage : Battery voltage
LDIA0070E