ECU INFINITI QX4 2001 Factory Service Manual

Item [Unit]Monitor item
Remarks
ECU input
signalsMain sig-
nalsItem menu
selection
Duty solenoid valve [%]
(Transfer 4WD solenoid valve)qH
2-4WD shift solenoid valve [ON-OFF]qH
Control signal outputs of transfer control unit Transfer motor relay [ON-OFF]qH
Shift activating 1 [ON-OFF]qH
Shift activating 2 [ON-OFF]qH
2-4WD shift solenoid valve monitor
[ON-OFF]H
Check signal (re-input signal) of transfer control
unit control signal output is displayed. If circuit
is shorted or open, ON/OFF state does not
change. Transfer motor relay monitor [ON-OFF]H
Shift activating monitor 1 [ON-OFF]H
Shift activating monitor 2 [ON-OFF]H
4WD fail lamp [ON-OFF]qHTransfer control unit control signal output for
4WD warning lamp (left)
Shift position switch 1 [ON-OFF]qH
Shift position switch 2 [ON-OFF]qH
2WD indicator lamp [ON-OFF]HTransfer control unit control signal output for
4WD shift indicator lamp (rear)
AUTO indicator lamp [ON-OFF]HTransfer control unit control signal output for
4WD shift indicator lamp (front & rear)
LOCK indicator lamp [ON-OFF]HTransfer control unit control signal output for
4WD shift indicator lamp (center)
4LO indicator lamp [ON-OFF]HTransfer control unit control signal output for
4WD shift indicator lamp (right)
Offset at startingHAppears on monitor but does not function.
Clutch limit [N´m (kg-m, ft-lb)]HClutch force release limit value set in WORK
SUPPORT
Voltage [V]HValue measured by voltage probe is displayed.
Frequency [Hz]HValue measured by pulse probe is displayed. If
measurement is impossible, ª#º sign is dis-
played. ª#º sign is also displayed at the final
data value until the measurement result is
obtained.
DUTY-HIH
Duty cycle value for measurement probe is dis-
played.
DUTY-LOWH
PLS WIDTH-HIH
Measured pulse width of measurement probe is
displayed.
PLS WIDTH-LOWH
*: This item is indicated as ªCOMP CL TORQº.GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis with CONSULT-II (Cont'd)
TF-35

4 CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select ªECU INPUT SIGNALSº in Data Monitor.
3. Read out the value of ªVEHICLE SPEED SENSOR (FRONT)º while driving.
SMT773D
SMT974D
4. Check if the value changes according to accelerating and decelerating the vehicle.
OK or NG
OK©GO TO 6.
NG©GO TO 7.
VEHICLE SPEED SENSOR (FRONT REVOLUTION SENSOR)
Diagnostic Procedure (Cont'd)
TF-62

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.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
2-4WD SHIFT SOLENOID VALVE AND 4WD SHIFT SWITCH
Diagnostic Procedure (Cont'd)
TF-67

4 CHECK INPUT SIGNAL
SMT784D
With CONSULT-II
1. Start engine.
2. Select ªECU INPUT SIGNALSº in Data Monitor.
3. Read out the value of ªFLUID TEMP SEº.
Voltage:
20ÉC (68ÉF): Approx. 1.5V
80ÉC (176ÉF): Approx. 0.5V
SMT974D
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
TRANSFER FLUID TEMPERATURE SENSOR
Diagnostic Procedure (Cont'd)
TF-74

4 CHECK INPUT SIGNAL
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out the ON/OFF status of ªATP SWº, ªNEUTRAL SWº and ªWAIT DETCT SWº.
SMT976D
OK or NG
OK©GO TO 6.
NG©Check the following.
IHarness continuity between transfer switch assembly sub-harness connector and
transfer control unit
IContinuity between transfer switch assembly sub-harness connector and body ground
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ATP SWITCH, WAIT DETECTION SWITCH AND NEUTRAL-4LO SWITCH
Diagnostic Procedure (Cont'd)
TF-77

5 CHECK INPUT SIGNAL
With CONSULT-II
1. Turn ignition switch to ªONº position.
2. Select ªECU INPUT SIGNALSº in Data Monitor.
3. Read out ON/OFF status of ªCL PRES SWº.
SMT788D
SMT977D
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.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
CLUTCH PRESSURE SWITCH
Diagnostic Procedure (Cont'd)
TF-81

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

Symptom 8. Tight Corner Braking SymptomNBTF0036SYMPTOM: Tight corner braking symptom occurs. (Hydraulic
system failure)
1 CHECK INPUT SIGNAL
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out the ON/OFF status of ªCLUTCH PRES SWº.
SMT977D
Without CONSULT-II
Check voltage between transfer control unit harness connector terminal 34 and body ground.
Refer to ªTRANSFER CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONº,
TF-55.
OK or NG
OK©Disassemble transfer unit and check the following.
IControl valve assembly
I4WD solenoid valve
I2-4WD shift solenoid valve
IClutch piston
IClutch assembly
NG©GO TO 2.
2 CHECK CLUTCH PRESSURE SWITCH CIRCUIT
Check clutch pressure switch circuit.
Refer to ªDiagnostic Procedureº, ªCLUTCH PRESSURE SWITCHº, TF-80.
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's pin terminals for damage or loose connection.
TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 8. Tight Corner Braking Symptom
TF-108

Symptom 9. 4WD System Does Not Operate=NBTF0037SYMPTOM: The vehicle cannot be put into 4WD mode.
(Hydraulic system failure)
1 CHECK INPUT SIGNAL
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out the ON/OFF status of ªCLUTCH PRES SWº.
SMT977D
Without CONSULT-II
Check voltage between transfer control unit harness connector terminal 34 and body ground.
Refer to ªTRANSFER CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONº,
TF-55.
OK or NG
OK©1. Check transfer fluid level.
2. Disassemble transfer unit and check the following.
ITransfer motor
IMain oil pump assembly
ISub-oil pump assembly
IOil strainer
IControl valve assembly
I2-4WD shift solenoid valve
IOil filter element
ILip seal
IStrainer O-ring
IMain oil pump drive gear
ISeal ring
ID-ring
IClutch piston
IClutch assembly
NG©GO TO 2.
2 CHECK CLUTCH PRESSURE CIRCUIT
Check clutch pressure switch circuit.
Refer to ªDiagnostic Procedureº, ªCLUTCH PRESSURE SWITCHº, TF-80.
OK or NG
OK©GO TO 3.
NG©Check, repair or replace faulty parts.
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 9. 4WD System Does Not Operate
TF-109

SMT897C
RemovalNBTF00731. Remove exhaust front and rear tubes. Refer to FE-8,
ªEXHAUST SYSTEMº.
2. Remove front and rear propeller shaft. Refer to PD-6,
ªRemoval and Installationº.
3. Insert plug into rear oil seal after removing propeller shaft.
IBe careful not to damage spline, sleeve yoke and rear oil
seal, when removing propeller shaft.
4. Disconnect neutral-4LO switch, front revolution sensor, ATP
switch, transfer motor and 4WD shift switch harness connec-
tors.
SMT808D
5. Remove center console and A/T control device.
6. Remove floor panel for transfer.
7. Remove upper side fixing bolt for A/T and TF.
8. Remove actuator lever from transfer outer shift lever and
remove sub-oil pump from transfer.
9. Remove remaining fixing bolt for AT and TF.
SMT899C
SMT871C
10. Remove transfer from transmission.
WARNING:
Support transfer while removing it.
SMT872C
InstallationNBTF0074ITighten bolts securing transfer.
Bolt length:
45 mm (1.77 in)
Tightening torque:
: 31 - 42 N´m (3.2 - 4.3 kg-m, 23 - 31 ft-lb)
GI
MA
EM
LC
EC
FE
AT
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
REMOVAL AND INSTALLATION
Removal
TF-119