2001 INFINITI QX4 Transfer Control Unit

6 CHECK INPUT SIGNAL
Without CONSULT-II
1. Turn ignition switch to ªONº position and set 4WD shift switch to ª4Hº position.
2. Check voltage between transfer control unit harness connector terminal 34 and body ground.
When 4WD shift switch is in ª2WDº:
Battery voltage should exist.
When 4WD shift switch is in ªAUTOº or ª4Hº and A/T selector lever is in ªDº:
ªWaitº operating: Battery voltage should exist.
ªWaitº not operating: Approx. 0 volts should exist.
SMT789D
SMT849D
OK or NG
OK©GO TO 7.
NG©Check the following.
IContinuity between transfer control unit and transfer terminal cord assembly sub-har-
ness connector
ITransfer sub-harness
IClutch pressure switch
Refer to ª4WD Solenoid Valve, Clutch Pressure Switch and Line Pressure Switchº,
ªCOMPONENT INSPECTIONº, TF-111.
7 PERFORM SELF-DIAGNOSIS AGAIN
1. Check hydraulic parts.
2. 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, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
CLUTCH PRESSURE SWITCH
Diagnostic Procedure (Cont'd)
TF-82

4 CHECK INPUT SIGNAL
SMT790D
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out the ON/OFF status of ªLINE PRES SWº.
SMT977D
OK or NG
OK©GO TO 6.
NG©Check the following.
IContinuity between transfer control unit and transfer terminal cord assembly sub-har-
ness connector
ITransfer sub-harness
ILine pressure switch
Refer to ª4WD Solenoid Valve, Clutch Pressure Switch and Line Pressure Switchº,
ªCOMPONENT INSPECTIONº, TF-111.
LINE PRESSURE SWITCH
Diagnostic Procedure (Cont'd)
TF-84

5 CHECK INPUT SIGNAL
Without CONSULT-II
1. Turn ignition switch to ªOFFº position.
2. Disconnect transfer control unit harness connector.
3. Check continuity between transfer control unit harness connector terminal 35 and body ground.
After the vehicle has been left for at least 5 minutes in a room temperature with ignition switch ªOFFº:
No continuity should exist.
With ignition switch in ªONº, 4WD shift switch in ªAUTOº or ª4Hº and A/T selector lever in ªDº:
Continuity should exist.
SMT791D
SMT849D
OK or NG
OK©GO TO 6.
NG©Check the following.
IContinuity between transfer control unit and transfer terminal cord assembly sub-har-
ness connector
ITransfer sub-harness
ILine pressure switch
Refer to ª4WD Solenoid Valve, Clutch Pressure Switch and Line Pressure Switchº,
ªCOMPONENT INSPECTIONº, TF-111.
6 PERFORM SELF-DIAGNOSIS AGAIN
1. Check hydraulic parts.
2. 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 TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
LINE PRESSURE SWITCH
Diagnostic Procedure (Cont'd)
TF-85

Diagnostic ProcedureNBTF0027
1 CHECK INPUT SIGNAL
WITHOUT CONSULT-II©GO TO 2.
2 CHECK INPUT SIGNAL
Without CONSULT-II
1. Turn ignition switch to ªOFFº position.
2. Disconnect ABS control unit harness connector.
3. Disconnect ABS control unit and transfer control unit harness connectors.
4. Check continuity between transfer control unit harness connector terminal 32 and ABS control unit harness connector
terminal 13.
Continuity should exist.
5. Check continuity between transfer control unit harness connector terminal 32, ABS control unit harness connector ter-
minal 13 and body ground.
No continuity should exist.
SMT793DA
OK or NG
OK©GO TO 3.
NG©Repair or replace harness or connector between ABS control unit and transfer control
unit.
3 CHECK COMMUNICATION LINE
Check communication line between ABS control unit and transfer control unit.
(Refer to BR-77, ª8. Vehicle vibrates excessively when ABS is operatingº.)
OK or NG
OK©GO TO 4.
NG©Check, repair or replace faulty parts.
ABS OPERATION SIGNAL
Diagnostic Procedure
TF-86

4 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.GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ABS OPERATION SIGNAL
Diagnostic Procedure (Cont'd)
TF-87

Diagnostic ProcedureNBTF0028
1 CHECK TRANSFER CONTROL UNIT POWER SOURCE
1. Turn ignition switch to ªOFFº position and perform self-diagnosis again.
Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27 and ªTrouble Diagnosis with CONSULT-IIº, TF-30.
2. Turn ignition switch to ªOFFº position.
3. Disconnect transfer control unit harness connector.
4. Check voltage between transfer control unit harness connector terminal 47 and body ground.
Voltage: Battery voltage
SMT794D
OK or NG
OK©GO TO 2.
NG©Check the following.
INo. 24 fuse (7.5A)
IHarness continuity between fuse and transfer control unit
2 PERFORM SELF-DIAGNOSIS AGAIN
After driving for a while, perform self-diagnosis again.
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, ªTROUBLE DIAGNOSIS Ð GENERAL
DESCRIPTIONº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
DATA ERASE/DISPLAY
Diagnostic Procedure
TF-88

5 CHECK INPUT SIGNAL
Without CONSULT-II
1. Start engine (idling).
2. Check voltage between transfer control unit harness connector terminal 33 (or 42) and body ground while 4WD shift
switch is set from 4H to 4LO (or from 4LO to 4H).
SMT828D
3. Result
MTBL0202
OK or NG
OK©GO TO 7.
NG©GO TO 6.
6 CHECK HARNESS CONTINUITY BETWEEN TRANSFER CONTROL UNIT AND TRANSFER CONTROL
DEVICE
OK or NG
OK©GO TO 7.
NG©Repair and replace harness connector between transfer control unit and transfer control
device.
7 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/output signal inspection. Refer to ªTRANSFER CON-
TROL 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.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
SHIFT ACTUATOR
Diagnostic Procedure (Cont'd)
TF-91

5 CHECK INPUT SIGNAL
Without CONSULT-II
1. Start engine (idling).
2. Check voltage transfer control unit harness connector terminal 27 (or 44) and body ground while 4WD shift switch is
set from 4H to 4LO (or from 4LO to 4H).
SMT830D
3. Result
MTBL0203
OK or NG
OK©GO TO 7.
NG©GO TO 6.
6 CHECK HARNESS CONTINUITY BETWEEN TRANSFER CONTROL UNIT AND TRANSFER CONTROL
DEVICE
OK or NG
OK©GO TO 7.
NG©Repair and replace harness connector between transfer control unit and transfer control
device.
7 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/output signal inspection. Refer to ªTRANSFER CON-
TROL 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.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
SHIFT ACTUATOR POSITION SWITCH
Diagnostic Procedure (Cont'd)
TF-93