2006 INFINITI QX56 ESP

TROUBLE DIAGNOSISAT-59
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Revision: November 2009 2006 QX56
2. CHECK SHIFT-UP D1 → D2
Press the accelerator pedal down all the way and inspect whether or not the transmission shifts up (D1 → D2)
at the correct speed.

Refer to AT- 6 0 , "Vehicle Speed When Shifting Gears" .
With CONSULT-II
Read the gear position, throttle position and vehicle speed.
Does the A/T shift-up D1
→ D2 at the correct speed?
YES >> GO TO 3.
NO >> Enter a check mark at “Vehicle Does Not Shift: D1 → D2 ” on the diagnostics worksheet, then con-
tinue the road test.
3. CHECK SHIFT-UP D2 → D3
Press the accelerator pedal down all the way and inspect whether or not the transmission shifts up (D2 → D3)
at the correct speed.

Refer to AT- 6 0 , "Vehicle Speed When Shifting Gears" .
With CONSULT-II
Read the gear position, throttle position and vehicle speed.
Does the A/T shift-up D2
→ D3 at the correct speed?
YES >> GO TO 4.
NO >> Enter a check mark at “Vehicle Does Not Shift: D2 → D3 ” on the diagnostics worksheet, then con-
tinue the road test.
4. CHECK SHIFT-UP D3 → D4 AND ENGINE BRAKE
When the transmission changes speed D3 → D4, return the accelerator pedal.
Does the A/T shift-up D3
→ D4 and apply the engine brake?
YES >> 1. Stop the vehicle.
2. See AT- 5 9 , "
Cruise Test - Part 3" .
NO >> Enter a check mark at “Vehicle Does Not Shift: D3 → D4 ” on the diagnostics worksheet, then con-
tinue the road test.
Cruise Test - Part 3ECS00CEJ
1. CHECK SHIFT-DOWN
During D
5 driving, move gear selector from D → 4 → 3 → 2 → 1.
With CONSULT-II
Read the gear position.
Is downshifting correctly performed?
YES >> GO TO 2.
NO >> Enter a check mark at “Vehicle does not shift ” at the corresponding position (5th → 4th, 4th → 3rd,
3rd → 2nd, 2nd → 1st) on the diagnostics worksheet, then continue the road test.
2. CHECK ENGINE BRAKE
Does engine braking effectively reduce speed in 1
1 position?
YES >> 1. Stop the vehicle. 2. Carry out the self-diagnostics. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
NO >> Enter a check mark at “Vehicle Does Not Decelerate By Engine Brake ” on the diagnostics work-
sheet, then continue trouble diagnosis.

DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)AT-111
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Revision: November 2009 2006 QX56
DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)PFP:32702
DescriptionECS00CFA
The revolution sensor detects the revolution of the idler gear parking pawl lock gear and emits a pulse signal.
The pulse signal is sent to the TCM which converts it into vehicle speed.
CONSULT-II Reference ValueECS00CFB
On Board Diagnosis LogicECS00CFC

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0720 VEH SPD SEN/CIR AT ” with CONSULT-II is detected under the following
conditions.
–When TCM does not receive the proper voltage signal from the sensor.
–After ignition switch is turned “ON”, irregular signal input from vehicle speed sensor MTR before the vehi-
cle starts moving.
Possible CauseECS00CFD

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

Revolution sensor

Vehicle speed sensor MTR
DTC Confirmation ProcedureECS00CFE
CAUTION:

Always drive vehicle at a safe speed.

Be careful not to rev engine into the red zone on the tachometer.
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. Drive vehicle and check for an increase of “VHCL/S SE·A/T ”
value in response to “VHCL/S SE·MTR ” value.
If the check result is NG, go to AT- 11 4 , "
Diagnostic Procedure" .
If the check result is OK, go to following step.
4. Select “DATA MONITOR” mode for “ENGINE ” with CONSULT-II.
5. Start engine and maintain the following conditions for at least 5 consecutive seconds.
VHCL SPEED SE: 30 km/h (19 MPH) or more
THRTL POS SEN: More than 1.0/8
Selector lever: “D” position
Driving location: Driving the vehicle uphill (increased engine load) will help maintain the driving
conditions required for this test.
If the check result is NG, go to AT- 11 4 , "
Diagnostic Procedure" .
If the check result is OK, go to following step.
6. Maintain the following conditions for at least 5 consecutive seconds. ENGINE SPEED: 3,500 rpm or more
THRTL POS SEN: More than 1.0/8
Selector lever: “D” position
Driving location: Driving the vehicle uphill (increased engine load) will help maintain the driving
conditions required for this test.
If the check result is NG, go to AT- 11 4 , "
Diagnostic Procedure" .
Item name Condition Display value (km/h)
VHCL/S SE ·A/T During driving Approximately matches the speedometer reading.
BCIA0030E

DTC P0725 ENGINE SPEED SIGNALAT-117
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Revision: November 2009 2006 QX56
2. CHECK DTC WITH TCM
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. While monitoring engine speed, check for engine speed change corresponding to wide-open throttle position signal.
OK or NG
OK >> GO TO 3.
NG >> Check the ignition signal circuit.

Refer to EC-618, "IGNITION SIGNAL" .
3. CHECK DTC
Perform "DTC Confirmation Procedure".

Refer to AT- 11 6 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 4.
4. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to AT- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
5. DETECT MALFUNCTIONING ITEM
Check the following items:

The A/T assembly harness connector pin terminals for damage or loose connection with harness connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
Item name Condition Display value (rpm)
ENGINE SPEED Engine running Closely matches the tachometer reading.
PCIA0041E

AT-118
DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVE
Revision: November 20092006 QX56
DTC P0740 TORQUE CONVERTER CLUTCH SOLENOID VALVEPFP:31940
DescriptionECS00CFN

The torque converter clutch solenoid valve is activated, with the gear in D4 , D5 by the TCM in response
to signals sent from the vehicle speed sensor and accelerator pedal position sensor (throttle position sen-
sor). Torque converter clutch piston operation will then be controlled.

Lock-up operation, however, is prohibited when A/T fluid temperature is too low.

When the accelerator pedal is depressed (less than 1/8) in lock-up condition, the engine speed should not
change abruptly. If there is a big jump in engine speed, there is no lock-up.
CONSULT-II Reference ValueECS00CFO
On Board Diagnosis LogicECS00CFP

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0740 TCC SOLENOID/CIRC ” with CONSULT-II is detected under the following
conditions.
–When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
–When TCM detects as irregular by comparing target value with monitor value.
Possible CauseECS00CFQ

Torque converter clutch solenoid valve

Harness or connectors
(The solenoid circuit is open or shorted.)
DTC Confirmation ProcedureECS00CFR
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. Turn ignition switch “ ON”. (Do not start engine.)
2. Select “DATA MONITOR ” mode for “ENGINE ” with CONSULT-II.
3. Start engine and maintain the following conditions for at least 5 consecutive seconds.
VHCL SPEED SE: 80 km/h (50 MPH) or more
ACCELE POS: 0.5/8 - 1.0/8
SELECTOR LEVER: “D” position
Driving location: Driving the vehicle uphill (increased
engine load) will help maintain the driving conditions
required for this test.
4. If DTC is detected go to AT- 11 9 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value (Approx.)
TCC SOLENOID When performing slip lock-up
0.2 - 0.4 A
When performing lock-up 0.4 - 0.6 A
BCIA0030E

AT-122
DTC P0745 LINE PRESSURE SOLENOID VALVE
Revision: November 20092006 QX56
DTC P0745 LINE PRESSURE SOLENOID VALVEPFP:31940
DescriptionECS00CFZ
The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in
response to a signal sent from the TCM.
The line pressure duty cycle value is not consistent when the closed throttle position signal is “ON”.
To confirm the line pressure duty cycle at low pressure, the accelerator (throttle) should be open until
the closed throttle position signal is “OFF”.
CONSULT-II Reference ValueECS00CG0
On Board Diagnosis LogicECS00CG1

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0745 L/PRESS SOL/CIRC” with CONSULT-II is detected under the following
conditions.
–When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
–When TCM detects as irregular by comparing target value with monitor value.
Possible CauseECS00CG2

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

Line pressure solenoid valve
DTC Confirmation ProcedureECS00CG3
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 ” and select “DATA MONITOR” mode for
“ENGINE ” with CONSULT-II.
2. Engine start and wait at least 5 second.
3. If DTC is detected, go to AT- 1 2 3 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value (Approx.)
LINE PRES SOL During driving0.2 - 0.6 A
BCIA0030E

DTC P1730 A/T INTERLOCKAT-135
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Revision: November 2009 2006 QX56
Judgement of A/T InterlockECS00CH9
When A/T Interlock is judged to be malfunctioning, the vehicle should be fixed in 2nd gear, and should be set
in a condition in which it can travel.
When one of the following fastening patterns is detected, the fail-safe function in correspondence with the indi-
vidual pattern should be performed.
A/T INTERLOCK COUPLING PATTERN TABLE

: NG, X: OK
Diagnostic ProcedureECS00CHA
1. SELF-DIAGNOSIS
With CONSULT-II
1. Drive vehicle.
2. Stop vehicle and turn ignition switch “OFF”.
3. Turn ignition switch “ON”.
4. Select “SELF-DIAG RESULTS” mode for “A/T ” with CONSULT-
II.
OK or NG
OK >> GO TO 2.
NG >> Check low coast brake solenoid valve circuit and func- tion. Refer to AT- 1 5 5 , "
DTC P1772 LOW COAST
BRAKE SOLENOID VALVE" , AT- 1 5 7 , "DTC P1774
LOW COAST BRAKE SOLENOID VALVE FUNCTION" .
2. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 3 4 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 3.
3. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to AT- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
Gear position ATF pressure switch output
Fail-safe function Clutch 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 interlock
coupling pat-
tern 3rd
–XX –
Held in
2nd gear OFF OFF ON OFF OFF OFF
4th –XX –
Held in
2nd gear OFF OFF ON OFF OFF OFF
5th X X –X
Held in
2nd gear OFF OFF ON OFF OFF OFF
BCIA0031E

DTC P1752 INPUT CLUTCH SOLENOID VALVEAT-139
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Revision: November 2009 2006 QX56
DTC P1752 INPUT CLUTCH SOLENOID VALVEPFP:31940
DescriptionECS00CHH
Input clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle
speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the
optimum position.
CONSULT-II Reference ValueECS00CHI
On Board Diagnosis LogicECS00CHJ

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P1752 I/C SOLENOID/CIRC ” with CONSULT-II is detected under the following
conditions.
–When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
–When TCM detects as irregular by comparing target value with monitor value.
Possible CauseECS00CHK

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

Input clutch solenoid valve
DTC Confirmation ProcedureECS00CHL
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. Turn ignition switch “ON”. (Do not start engine.)
2. Select “DATA MONITOR ” mode for “A/T” with CONSULT-II.
3. Start engine.
4. Drive vehicle and maintain the following conditions for at least 5 consecutive seconds.
ACCELE POS: 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.
5. If DTC is detected go to AT- 1 4 0 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value (Approx.)
I/C SOLENOID Input clutch disengaged. Refer to
AT- 2 0
.0.6 - 0.8 A
Input clutch engaged. Refer to AT- 2 0
.0 - 0.05 A
BCIA0030E

DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTIONAT-141
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Revision: November 2009 2006 QX56
DTC P1754 INPUT CLUTCH SOLENOID VALVE FUNCTIONPFP:31940
DescriptionECS00CHN

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 ValueECS00CHO
On Board Diagnosis LogicECS00CHP

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P1754 I/C SOLENOID FNCTN” with 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 CauseECS00CHQ

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

Input clutch solenoid valve

ATF pressure switch 3
DTC Confirmation ProcedureECS00CHR
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- 1 4 2 , "
Diagnostic Procedure" .
If DTC (P1752) is detected, go to AT- 1 4 0 , "
Diagnostic Procedure" .
If DTC (P1843) is detected, go to AT- 1 6 2 , "
Diagnostic Procedure" .
Item nameCondition Display value (Approx.)
I/C SOLENOID Input clutch disengaged. Refer to
AT- 2 0
.0.6 - 0.8 A
Input clutch engaged. Refer to AT- 2 0
.0 - 0.05 A
ATF PRES SW 3 Input clutch engaged. Refer to
AT- 2 0
.ON
Input clutch disengaged. Refer to AT- 2 0
.OFF
BCIA0030E