Electric INFINITI QX56 2004 Factory Owner's Manual

AT-44
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
A/T Interlock

If there is an A/T interlock judgment malfunction, the transmission is fixed in 2nd gear to make driving pos-
sible.
NOTE:
When the vehicle is driven fixed in 2nd gear, a turbine revolution sensor malfunction is displayed,
but this is not a turbine revolution sensor malfunction.

When the coupling pattern below is detected, the fail-safe action corresponding to the pattern is per-
formed.
A/T INTERLOCK COUPLING PATTERN TABLE

: NG X: OK
A/T 1st Engine Braking

When there is an A/T first gear engine brake judgment malfunction, the low coast brake solenoid is
switched “OFF” to avoid the engine brake operation.
Line Pressure Solenoid

The solenoid is switched “OFF” and the line pressure is set to the maximum hydraulic pressure to make
driving possible.
Torque Converter Clutch Solenoid

The solenoid is switched “OFF” to release the lock-up.
Low Coast Brake Solenoid

When a (electrical or functional) malfunction occurs, in order to make driving possible, the engine brake is
not applied in 1st and 2nd gear.
Input Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Direct Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Front Brake Solenoid

If a (electrical or functional) malfunction occurs with the solenoid “ON”, in order to make driving possible,
the A/T is held in 5th gear; if the solenoid is OFF, 4th gear.
High and Low Reverse Clutch Solenoid

If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Turbine Revolution Sensor 1 or 2

The control is the same as if there were no turbine revolution sensors, 5th gear is prohibited.
Gear positionATF pressure switch output
Fail-safe
functionClutch pressure output pattern after fail-safe func-
tion
SW3
(I/C)SW6
(HLR/
C)SW5
(D/C)SW1
(Fr/B)SW2
(LC/B)I/C HLR/C D/C Fr/B LC/B L/U
A/T inter-
lock cou-
pling pattern3rd – X X –
Held in
2nd gearOFF OFF ON OFF OFF OFF
4th – X X –
Held in
2nd gearOFF OFF ON OFF OFF OFF
5th X X – X
Held in
2nd gearOFF OFF ON OFF OFF OFF

TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
How To Perform Trouble Diagnosis For Quick and Accurate RepairUCS002CT
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelerator pedal position sensor (throttle position
sensor) or PNP switch and provides shift control or lock-up control via A/T solenoid valves.
The TCM also communicates with the ECM by means of a signal
sent from sensing elements used with the OBD-related parts of the
A/T system for malfunction-diagnostic purposes. The TCM is capa-
ble of diagnosing malfunctioning parts while the ECM can store mal-
functions in its memory.
Input and output signals must always be correct and stable in the
operation of the A/T system. The A/T system must be in good oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose a error that occurs intermittently
rather than continuously. Most intermittent errors are caused by poor
electric connections or improper wiring. In this case, careful check-
ing of suspected circuits may help prevent the replacement of good
parts.
A visual check only may not find the cause of the errors. A road test
with CONSULT-II (or GST) or a circuit tester connected should be
performed. Follow the AT-46, "
WORK FLOW" .
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “Diagnostic Worksheet” as shown on
the example (Refer to AT- 4 7
) should be used.
Start your diagnosis by looking for “conventional” errors first. This will
help troubleshoot driveability errors on an electronically controlled
engine vehicle.
Also check related Service bulletins.
SAT6 3 1IB
SAT6 3 2I
SEF 2 34 G

AT-50
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
A/T Electrical Parts LocationUCS002CU
BCIA0028E

TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
CONSULT-II Function (A/T)UCS002D8
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
CONSULT-II REFERENCE VALUE
NOTICE:
1. The CONSULT-II electrically displays shift timing and lock-up timing (that is, operation timing of each sole-
noid).
Check for time difference between actual shift timing and the CONSULT-II display. If the difference is
noticeable, mechanical parts (except solenoids, sensors, etc.) may be malfunctioning. Check mechanical
parts using applicable diagnostic procedures.
2. Shift schedule (which implies gear position) displayed on CONSULT-II and that indicated in Service Man-
ual may differ slightly. This occurs because of the following reasons:
–Actual shift schedule has more or less tolerance or allowance,
–Shift schedule indicated in Service Manual refers to the point where shifts start, and
–Gear position displayed on CONSULT-II indicates the point where shifts are completed.
3. Display of solenoid valves on CONSULT-II changes at the start of shifting, while gear position is displayed
upon completion of shifting (which is computed by TCM).
TCM diagnostic mode Description
WORK SUPPORTSupports inspections and adjustments. Commands are transmitted to the TCM for setting the status
suitable for required operation, input/output signals are received from the TCM and received data is
displayed.
SELF-DIAG RESULTS Displays TCM self-diagnosis results.
DATA MONITOR Displays TCM input/output data in real time.
CAN DIAG SUPPORT MNTR The result of transmit/receive diagnosis of CAN communication can be read.
ACTIVE TEST Operation of electrical loads can be checked by sending drive signal to them.
FUNCTION TESTConducted by CONSULT-II instead of a technician to determine whether each system is “OK” or
“NG”.
ECU PART NUMBER TCM part number can be read.
Item name Condition Display value
AT F T E M P S E 1
0°C (32° F) - 20°C (68°F) - 80°C (176°F)3.2 - 2.5 - 0.8 V
AT F T E M P S E 23.2 - 2.4 - 0.65 V
TCC SOLENOIDWhen perform slip lock-up 0.2 - 0.4 A
When perform lock-up 0.4 - 0.6 A
SLCT LVR POSISelector lever in “N”,“P” position. N/P
Selector lever in “R” position. R
Selector lever in “D” position. D
Selector lever in “4” position. 4
Selector lever in “3” position. 3
Selector lever in “2” position. 2
Selector lever in “1” position. 1
VHCL/S SE·A/T During driving Approximately matches the
speedometer reading.
ENGINE SPEED Engine running Closely matches the tachometer
reading.
LINE PRES SOL During driving 0.2 - 0.6 A
TURBINE REV During driving (lock-up ON) Approximately matches the
engine speed.
VHCL/S SE·MTR During driving Approximately matches the
speedometer reading.

AT-94
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Display Items List
X: Applicable, —: Not applicable
Items (CONSULT-II
screen terms)Malfunction is detected when...TCM self-
diagnosisOBD-II (DTC)
“A/T” with
CONSULT-IIMIL indicator
lamp*1,
“ENGINE” with
CONSULT-II or
GST
CAN COMM CIRCUIT

When a malfunction is detected in CAN communications U1000 U1000
STARTER RELAY/
CIRC

If this signal is ON other than in P or N position, this is judged to be a
malfunction.
(And if it is OFF in P or N position, this too is judged to be a malfunc-
tion.)P0615 —
TCM

TCM is malfunctioning. P0700 P0700
PNP SW/CIRC

PNP switch 1-4 signals input with impossible pattern

PNP switch 3 monitor terminal cut line

“P” position is detected from N position without any other position
being detected in between.P0705 P0705
VEH SPD SEN/CIR AT
(Revolution sensor)

Signal from vehicle speed sensor A/T (Revolution sensor) not input
due to cut line or the like

Unexpected signal input during running

After ignition switch is turned ON, unexpected signal input from vehicle
speed sensor MTR before the vehicle starts movingP0720 P0720
ENGINE SPEED SIG

TCM does not receive the CAN communication signal from the ECM. P0725 —
TCC SOLENOID/CIRC

Normal voltage not applied to solenoid due to cut line, short, or the like P0740 P0740
A/T TCC S/V FNCTN

A/T cannot perform lock-up even if electrical circuit is good.

TCM detects as irregular by comparing difference value with slip rota-
tion.P0744 P0744*2
L/PRESS SOL/CIRC

Normal voltage not applied to solenoid due to cut line, short, or the like

TCM detects as irregular by comparing target value with monitor value.P0745 P0745
TCM·RAM

TCM memory (RAM) is malfunctioning. P1702 —
TCM·ROM

TCM memory (ROM) is malfunctioning. P1703 —
TP SEN/CIRC A/T

TCM does not receive the proper accelerator pedal position signals
(input by CAN communication) from ECM.P1705 P1705
ATF TEMP SEN/CIRC

During running, the ATF temperature sensor signal voltage is exces-
sively high or lowP1710 P0710
TURBINE REV S/CIRC

TCM does not receive the proper voltage signal from the sensor.

TCM detects an irregularity only at position of 4th gear for turbine revo-
lution sensor 2.P1716 P1716
VEH SPD SE/CIR·MTR

Signal (CAN communication) from vehicle speed sensor MTR not input
due to cut line or the like

Unexpected signal input during runningP1721 —
A/T INTERLOCK

Except during shift change, the gear position and ATF pressure switch
states are monitored and comparative judgement made.P1730 P1730
A/T 1ST E/BRAKING

Each ATF pressure switch and solenoid current is monitored and if a
pattern is detected having engine braking 1st gear other than in the M1
position, a malfunction is detected.P1731 —
I/C SOLENOID/CIRC

Normal voltage not applied to solenoid due to functional malfunction,
cut line, short, or the like

TCM detects as irregular by comparing target value with monitor value.P1752 P1752

DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)
AT-121
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Revision: August 20072004 QX56
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)PFP:31940
DescriptionUCS002ED
This malfunction is detected when the A/T does not shift into 5th gear position or the torque converter clutch
does not lock-up as instructed by the TCM. This is not only caused by electrical malfunction (circuits open or
shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation,
etc.
CONSULT-II Reference ValueUCS002EE
On Board Diagnosis LogicUCS002EF

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “A/T TCC S/V FNCTN” with CONSULT-II or P0744 without CONSULT-II is
detected under the following conditions.
–When A/T cannot perform lock-up even if electrical circuit is good.
–When TCM detects as irregular by comparing difference value with slip rotation.
Possible CauseUCS002EG

Harness or connectors
(The solenoid circuit is open or shorted.)

Torque converter clutch solenoid valve

Hydraulic control circuit
DTC Confirmation ProcedureUCS002EH
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Start engine and Select “TCC S/V FNCTN CHECK” of “DTC
WORK SUPPORT” mode for “A/T” with CONSULT-II and touch
“START”.
2. Accelerate vehicle to more than 80 km/h (50 MPH) and maintain
the following condition continuously until “TESTING” has turned
to “COMPLETE”. (It will take approximately 30 seconds after
“TESTING” shows.)
ACCELE POSI: More than 1.0/8 (at all times during step 4)
TCC SOLENOID: 0.4 - 0.6 A
Selector lever: “D” position
[Reference speed: Constant speed of more than 80 km/h (50
MPH)]
–Make sure “GEAR” shows “5”.
–For shift schedule, refer to AT- 6 7 , "Vehicle Speed When Performing and Releasing Complete Lock-
up" .
–If “TESTING” does not appear on CONSULT-II for a long time, select “SELF-DIAG RESULTS”. In
case a 1st trip DTC other than P0744 is shown, refer to applicable “TROUBLE DIAGNOSIS FOR
DTC”.
3. Make sure that “OK” is displayed. (If “NG” is displayed, refer to “DIAGNOSTIC PROCEDURE”.)
Refer to AT- 1 2 2 , "
Diagnostic Procedure" .
Refer to shift schedule, AT-67, "
Vehicle Speed When Performing and Releasing Complete Lock-up" .
Item name Condition Display value (Approx.) (A)
TCC SOLENOIDWhen performing slip lock-up 0.2 - 0.4
When performing lock-up 0.4 - 0.6
BCIA0030E

DTC P1705 THROTTLE POSITION SENSOR
AT-129
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DTC P1705 THROTTLE POSITION SENSORPFP:22620
DescriptionUCS002EZ
Electric throttle control actuator consists of throttle control motor, accelerator pedal position sensor, throttle
position sensor, etc. The actuator sends a signal to the ECM, and ECM sends signals to TCM with CAN com-
munication.
CONSULT-II Reference ValueUCS002F0
On Board Diagnosis LogicUCS002F1

This is not an OBD-II self-diagnostic item.

Diagnostic trouble code “TP SEN/CIRC A/T” with CONSULT-II is detected when TCM does not receive
the proper accelerator pedal position signals (input by CAN communication) from ECM.
Possible CauseUCS002F2
Harness or connectors
(The sensor circuit is open or shorted.)
DTC Confirmation ProcedureUCS002F3
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “DATA MONITOR” mode for “A/T” with CONSULT-II.
3. Start engine and let it idle for 1 second.
4. If DTC is detected, go to AT - 1 2 9 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Diagnostic ProcedureUCS002F4
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT - 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 1 0 3 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
Item name Condition Display value (Approx.)
ACCELE POSIReleased accelerator pedal. 0.0/8
Fully depressed accelerator pedal. 8/8
THROTTLE POSIReleased accelerator pedal. 0.0/8
Fully depressed accelerator pedal. 8/8
BCIA0030E

AT-148
DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTION
Revision: August 20072004 QX56
DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTIONPFP:31940
DescriptionUCS002G6

Input clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehi-
cle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be
shifted to the optimum position.

This is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical mal-
function such as control valve sticking, improper solenoid valve operation.
CONSULT-II Reference ValueUCS002G7
On Board Diagnosis LogicUCS002G8

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “I/C SOLENOID FNCTN” with CONSULT-II or P1754 without CONSULT-II is
detected under the following conditions.
–When TCM detects that actual gear ratio is irregular, and relation between gear position and condition of
pressure switch 3 is irregular during depressing accelerator pedal. (Other than during shift change)
–When TCM detects that relation between gear position and condition of ATF pressure switch 3 is irregular
during releasing accelerator pedal. (Other than during shift change)
Possible CauseUCS002G9

Harness or connectors
(The solenoid and switch circuits are open or shorted.)

Input clutch solenoid valve

ATF pressure switch 3
DTC Confirmation ProcedureUCS002GA
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Start engine.
2. Accelerate vehicle to maintain the following conditions.
ACCELE POSI: 1.5/8 - 2.0/8
Selector lever: “D” position
Gear position: 3rd

4th Gear (I/C ON/OFF)
Driving location: Driving the vehicle uphill (increased
engine load) will help maintain the driving conditions
required for this test.
3. Perform step “2” again.
4. Turn ignition switch “OFF”, then perform step “1” to “3” again.
5. Check “SELF-DIAG RESULTS” mode for “A/T” with CONSULT-
II. If DTC (P1754) is detected, refer to AT-149, "
Diagnostic Procedure" .
If DTC (P1752) is detected, go to AT- 1 4 6 , "
Diagnostic Procedure" .
If DTC (P1843) is detected, go to AT- 1 7 9 , "
Diagnostic Procedure" .
Item name Condition Display value (Approx)
I/C SOLENOIDInput clutch disengaged. Refer to AT- 2 1
. 0.6 - 0.8 A
Input clutch engaged. Refer to AT- 2 1
. 0 - 0.05 A
ATF PRES SW 3Input clutch engaged. Refer to AT- 2 1
.ON
Input clutch disengaged. Refer to AT- 2 1
. OFF
BCIA0030E

DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTION
AT-149
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WITH GST
Follow the procedure “With CONSULT-II”.
Diagnostic ProcedureUCS002G B
1. CHECK INPUT SIGNALS
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II.
3. Start the engine.
4. Drive vehicle in the “D” position (3rd

4th gear), and confirm
the ON/OFF actuation of the “ATF PRES SW 3” and electrical
current value of “I/C SOLENOID”.
OK or NG
OK >> GO TO 6.
NG >> GO TO 2.
2. CHECK TCM
Perform TCM input/output signals inspection. Refer to AT-90, "
TCM Input/Output Signal Reference Values" .
OK or NG
OK >> GO TO 3.
NG >> GO TO 5.
3. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT- 1 4 8 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 4.
4. DETECT MALFUNCTIONING ITEM
Check the following items:

The A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT - 2 4 1 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
Item name Condition Display value (Approx)
I/C SOLE-
NOIDInput clutch disengaged. Refer to AT- 2 1
. 0.6 - 0.8 A
Input clutch engaged. Refer to AT- 2 1
. 0 - 0.05 A
ATF PRES
SW 3Input clutch engaged. Refer to AT- 2 1
.ON
Input clutch disengaged. Refer to AT- 2 1
. OFF
SCIA4795E

AT-154
DTC P1759 FRONT BRAKE SOLENOID VALVE FUNCTION
Revision: August 20072004 QX56
DTC P1759 FRONT BRAKE SOLENOID VALVE FUNCTIONPFP:31940
DescriptionUCS002G I

Front brake solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehi-
cle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be
shifted to the optimum position.

This is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical mal-
function such as control valve sticking, improper solenoid valve operation.
CONSULT-II Reference ValueUCS002GJ
On Board Diagnosis LogicUCS002GK

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “FR/B SOLENOID FNCT” with CONSULT-II or P1759 without CONSULT-II is
detected under the following conditions.
–When TCM detects that actual gear ratio is irregular, and relation between gear position and condition of
ATF pressure switch 1 is irregular during depressing accelerator pedal. (Other than during shift change)
–When TCM detects that relation between gear position and condition of ATF pressure switch 1 is irregular
during releasing accelerator pedal. (Other than during shift change)
Possible CauseUCS002GL

Harness or connectors
(The solenoid and switch circuits are open or shorted.)

Front brake solenoid valve

ATF pressure switch 1
DTC Confirmation ProcedureUCS002GM
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Start engine.
2. Accelerate vehicle to maintain the following conditions.
ACCELE POS: 1.5/8 - 2.0/8
Selector lever: “D” position
Gear position: 3rd

4th Gear (FR/B ON/OFF)
Driving location: Driving the vehicle uphill (increased
engine load) will help maintain the driving conditions
required for this test.
3. Perform step “2” again.
4. Turn ignition switch “OFF”, then perform step “1” to “3” again.
5. Check “SELF-DIAG RESULTS” mode for “A/T” with CONSULT-
II. If DTC (P1759) is detected, refer to AT-155, "
Diagnostic Procedure" .
If DTC (P1757) is detected, go to AT- 1 5 2 , "
Diagnostic Procedure" .
If DTC (P1841) is detected, go to AT- 1 7 6 , "
Diagnostic Procedure" .
Item name Condition Display value (Approx)
FR/B SOLENOIDFront brake engaged. Refer to AT- 2 1
. 0.6 - 0.8 A
Front brake disengaged. Refer to AT- 2 1
. 0 - 0.05 A
ATF PRES SW 1Front brake engaged. Refer to AT- 2 1
.ON
Front brake disengaged. Refer to AT- 2 1
. OFF
BCIA0030E