2001 INFINITI QX4 Transfer Control Unit

Terminal
No.Item Condition Judgement standard
31Transfer fluid tempera-
ture sensor
&
At 20ÉC (68ÉF) Approx. 1.5V
At 80ÉC (176ÉF) Approx. 0.5V
32 ABS signalWhen moving, use the CONSULT-II
pulse frequency measuirng func-
tion.*2
CAUTION:
Connect the diagnosis data link
cable to the vehicle diagnosis con-
nector.
*2: A circuit tester cannot be used to
test this item.Refer to the illustration
(SMT973D) at the end of
this section.
33Transfer shift relay
(High)While actuator is operating from ª4Hº
to ª4LOºBattery voltage
Actuator does not operate. Approx. 0V
34 Clutch pressure switch4WD shift switch is set to ªAUTOº or
ª4Hº, then A/T selector lever is set to
ªDº position. (wait detection system:
OFF)Battery voltage
4WD shift switch is set to ª2WDº,
ªAUTOº or ª4Hº, then A/T selector
lever is set to ªDº position. (wait
detection system: ON)Approx. 0V
35 Line pressure switch4WD shift switch is set to ª2WDº,
ªAUTOº or ª4Hº, then A/T selector
lever is set to ªDº position.Battery voltage
Ð Approx. 0V
36 CONSULT-II (RX) Ð Ð Ð
37 Tachometer
ÐRefer to EC-127, ªECM
Inspection Tableº.
38 Front revolution sensor
4WD shift switch is set to ª4Hº posi-
tion. A/T selector lever is set to ªDº
position.Approx. 1V [30 km/h (19
MPH)]
Voltage rises in
response to vehicle
speed.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-58

Terminal
No.Item Condition Judgement standard
39ECM (Throttle position
sensor)
&
Throttle valve is fully open. Approx. 0.5V
Throttle valve is closed. Approx. 4.2V
40 ATP switchA/T selector lever is set to ªPº posi-
tion.Battery voltage
A/T selector lever is set to any posi-
tion other than ªPº.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
ª4LOº to ª4Hº positionBattery voltage
Actuator does not operate. Approx. 0V
43 Wait detection switch4WD shift switch is set to any posi-
tion other than ª4LOº.Battery voltage
4WD shift switch is set to ª4LOº posi-
tion.*3Less than 1V
44Transfer 4LO actuator
switch4WD shift switch is set to any posi-
tion other than ª4LOº. (Actuator: High
position)Battery voltage
4WD shift switch is set to ª4LOº posi-
tion. (Actuator: Low position)Less than 1V
45 Ground Ð Ð Ð
46ÐÐÐÐ
47Power supply (memory
back up)
&Ð Battery voltage
48 CONSULT-II (TX) Ð Ð Ð
*3: While wait detection system is operating, terminal 43 exists battery voltage.
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-59

SMT973D
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-60

5 CHECK INPUT SIGNAL
Without CONSULT-II
1. Start engine.
2. Check voltage between transfer control unit harness connector terminals 38 and 28.
(Measure it in AC range.)
Voltage:
0 km/h (0 MPH): 0V
30 km/h (19 MPH): More than 1V
(Voltage rises gradually in response to vehicle speed.)
SMT774D
OK or NG
OK©GO TO 6.
NG©GO TO 7.
6 PERFORM SELF-DIAGNOSIS AGAIN
After driving for a while, perform self-diagnosis again.
Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27.
OK or NG
OK©INSPECTION END
NG©1. Perform transfer control unit input/output signal inspection. Refer to ªTRANSFER
CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL
DESCRIPTIONº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
7 CHECK HARNESS CONTINUITY BETWEEN TRANSFER CONTROL UNIT AND FRONT REVOLUTION
SENSOR SUB-HARNESS CONNECTOR
OK or NG
OK©GO TO 6.
NG©Repair or replace sub-harness connector between transfer control unit and front revolu-
tion sensor.
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VEHICLE SPEED SENSOR (FRONT REVOLUTION SENSOR)
Diagnostic Procedure (Cont'd)
TF-63

Diagnostic ProcedureNBTF0020
1 CHECK 4WD SOLENOID VALVE
SMT775D
Refer to ª4WD Solenoid Valve, Clutch Pressure Switch and Line Pressure Switchº, ªCOMPONENT INSPECTIONº, TF-111.
OK or NG
OK©GO TO 2.
NG©Check the following. If OK, repair or replace 4WD solenoid valve.
IContinuity of transfer sub-harness
Refer to ªTRANSFER TERMINAL CORD ASSEMBLY SUB-HARNESS CONNECTORº,
ªCOMPONENT INSPECTIONº, TF-114.
2 CHECK POWER SOURCE CIRCUIT
1. Turn ignition switch to ªOFFº position.
2. Disconnect transfer control unit harness connector.
3. Check resistance between transfer terminal cord assembly sub-harness connector terminal 6 and transfer control unit
harness connector terminal 10.
Resistance: 11.2 - 12.8W
SMT776D
OK or NG
OK©GO TO 3.
NG©Check the following.
ITransfer dropping resistor
Refer to ªTransfer Dropping Resistorº, ªCOMPONENT INSPECTIONº, TF-112.
IContinuity between transfer terminal cord assembly sub-harness connector terminal 6
and transfer control unit harness connector terminal 10.
4WD SOLENOID VALVE
Diagnostic Procedure
TF-64

3 CHECK POWER SOURCE CIRCUIT
1. Turn ignition switch to ªOFFº position.
2. Check continuity between transfer terminal cord assembly sub-harness connector terminal 6 and transfer control unit
harness connector terminal 19.
Continuity should exist.
SMT777D
OK or NG
OK©GO TO 4.
NG©Repair or replace harness between transfer terminal cord assembly sub-harness connec-
tor terminal 6 and transfer control unit harness connector terminal 19.
4 PERFORM SELF-DIAGNOSIS
After driving for a while, perform self-diagnosis.
Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27 and ªTrouble Diagnosis with CONSULT-IIº, TF-30.
OK or NG
OK©INSPECTION END
NG©1. Perform transfer control unit input/output signal inspection. Refer to ªTRANSFER
CONTROL UNIT INSPECTION TABLEº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
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4WD SOLENOID VALVE
Diagnostic Procedure (Cont'd)
TF-65

2 CHECK INPUT SIGNAL
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out ON/OFF status of ª2WD SWº and ªLOCK SWITCHº.
SMT974D
OK or NG
OK©1. Perform transfer control unit input/output signal inspection. Refer to ªTRANSFER
CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL
DESCRIPTIONº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
NG©GO TO 3.
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2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCH
Diagnostic Procedure (Cont'd)
TF-67

4 CHECK HARNESS CONTINUITY
1. Turn ignition switch to ªOFFº position.
2. Check continuity between the following terminals:
ITransfer control unit 9 and 4WD shift switch 2 (2WD)
ITransfer control unit 18 and 4WD shift switch 5 (4H)
ITransfer control unit 24 and 4WD shift switch 3 (AUTO)
ITransfer control unit 23 and 4WD shift switch 6 (4LO)
ITransfer control unit 1 and Transfer terminal cord assembly sub-harness connector 4
I4WD shift switch 4 and Transfer terminal cord assembly sub-harness connector 5
Continuity should exist.
SMT853D
OK or NG
OK©GO TO 5.
NG©Repair harness or connector.
5 PERFORM SELF-DIAGNOSIS AGAIN
After driving for a while, perform self-diagnosis again.
Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27.
OK or NG
OK©INSPECTION END
NG©1. Perform transfer control unit input/output signal inspection. Refer to ªTRANSFER
CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL
DESCRIPTIONº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
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2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCH
Diagnostic Procedure (Cont'd)
TF-69