2006 INFINITI QX56 ECU

AT-114
DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CFG
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Turn ignition switch “ ON”.
2. Select “ECU INPUT SIGNALS ” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. Start the engine.
4. Read out the value of “VHCL/S SE·A/T ” while driving.
Check the value changes according to driving speed.
OK or NG
OK >> GO TO 6.
NG >> GO TO 2.
2. 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 3.
NG >> Repair or replace damaged parts.
3. 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 >> GO TO 4.
NG >> Repair or replace damaged parts.
Item name Condition Display value (km/h)
VHCL/S SE ·A/T During driving Approximately matches the
speedometer reading.
SCIA2148E

AT-116
DTC P0725 ENGINE SPEED SIGNAL
Revision: November 20092006 QX56
DTC P0725 ENGINE SPEED SIGNALPFP:24825
DescriptionECS00CFH
The engine speed signal is sent from the ECM to the TCM.
CONSULT-II Reference ValueECS00CFI
On Board Diagnosis LogicECS00CFJ

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

Diagnostic trouble code “P0725 ENGINE SPEED SIG ” with CONSULT-II is detected when TCM does not
receive the ignition signal from ECM during engine cranking or running.
Possible CauseECS00CFK
Harness or connectors
(The ECM to the TCM circuit is open or shorted.)
DTC Confirmation ProcedureECS00CFL
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 ” and select “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
2. Start engine and maintain the following conditions for at least 10 consecutive seconds.
VHCL SPEED SE: 10 km/h (6 MPH) or more
ACCELE POSI: More than 1/8
Selector lever: “D” position
3. If DTC is detected, go to AT- 11 6 , "
Diagnostic Procedure" .
Diagnostic ProcedureECS00CFM
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 9 6 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
Item name Condition Display value (rpm)
ENGINE SPEED Engine running Closely matches the tachometer 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

DTC P1705 THROTTLE POSITION SENSORAT-125
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Revision: November 2009 2006 QX56
2. CHECK DTC WITH TCM
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. Depress accelerator pedal and read out the value of “ACCELE
POSI ”.
4. Select “SELF-DIAG RESULTS” mode for “A/T ” with CONSULT-
II. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. CHECK DTC WITH ECM
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “SELF-DIAG RESULTS” mode for “ENGINE” with CON-
SULT-II. Refer to AT- 8 4 , "
CONSULT-II Function (A/T)" .
OK or NG
OK >> GO TO 4.
NG >> Check the DTC detected item. Refer to AT- 8 4 , "
CON-
SULT-II Function (A/T)" .

If CAN communication line is detected, go to AT- 9 6 ,
"DTC U1000 CAN COMMUNICATION LINE" .
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 2 4 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 5.
5. 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 6.
NG >> Repair or replace damaged parts.
Item name Condition Display value
(Approx.)
ACCELE POSI Released accelerator pedal.
0.0/8
Fully depressed accelerator pedal. 8/8
PCIA0070E
BCIA0030E

DTC P1710 A/T FLUID TEMPERATURE SENSOR CIRCUITAT-129
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Revision: November 2009 2006 QX56
Diagnostic ProcedureECS00CGR
1. CHECK A/T FLUID TEMPERATURE SENSOR 1 SIGNAL
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. Read out the value of “ATF TEMP SE 1”.
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2. CHECK A/T FLUID TEMPERATURE SENSOR 2 SIGNAL
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. Read out the value of “ATF TEMP SE 2”.
OK or NG
OK >> GO TO 8.
NG >> GO TO 5.
3. CHECK A/T FLUID TEMPERATURE SENSOR 1
Check A/T fluid temperature sensor 1. Refer to AT- 1 3 0 , "
A/T FLUID TEMPERATURE SENSOR 1" .
OK or NG
OK >> GO TO 4.
NG >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "
Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
4. CHECK SUB-HARNESS
1. Disconnect park/neutral position switch connector and TCM connector.
2. Check continuity between park/neutral position switch connector terminals and TCM connector terminals.
3. If OK, check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> Replace open circuit or short to ground and short to power in harness or connectors.
Item name Condition °C ( °F) Display value (Approx.)
ATF TEMP SE 1 0 (32) - 20 (68) - 80 (176) 3.3 - 2.7 - 09 V
PCIA0039E
Item name Condition °C ( °F) Display value (Approx.)
ATF TEMP SE 2 0 (32) - 20 (68) - 80 (176) 3.3 - 2.5 - 0.7 V
PCIA0039E
Item Connector Terminal Continuity
Park/neutral position switch
connector F505
6
Ye s
TCM connector F50319
Park/neutral position switch
connector F505
7
Ye s
TCM connector F50318
SCIA5461E

AT-132
DTC P1721 VEHICLE SPEED SENSOR MTR
Revision: November 20092006 QX56
DTC P1721 VEHICLE SPEED SENSOR MTRPFP:24814
DescriptionECS00CGZ
The vehicle speed sensor·MTR signal is transmitted from combination meter to TCM by CAN communication
line. The signal functions as an auxiliary device to the revolution sensor when it is malfunctioning. The TCM
will then use the vehicle speed sensor ·MTR signal.
CONSULT-II Reference ValueECS00CH0
On Board Diagnosis LogicECS00CH1

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

Diagnostic trouble code “P1721 VHE SPD SE ·MTR ” with CONSULT-II is detected when TCM does not
receive the proper vehicle speed sensor MTR signal (input by CAN communication) from combination
meter.
Possible CauseECS00CH2
Harness or connectors
(The sensor circuit is open or shorted.)
DTC Confirmation ProcedureECS00CH3
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 and maintain the following conditions for at least 5 consecutive seconds.
ACCELE POS: 1/8 or less
VHCL SPEED SE: 30 km/h (17 MPH) or more
4. If DTC is detected, go to AT- 1 3 3 , "
Diagnostic Procedure" .
Item name Condition Display value (km/h)
VHCL/S SE ·MTR During driving Approximately matches the speedometer reading.
BCIA0030E

DTC P1721 VEHICLE SPEED SENSOR MTRAT-133
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Revision: November 2009 2006 QX56
Diagnostic ProcedureECS00CH4
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 9 6 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T ” with CONSULT-II.
3. Drive vehicle and read out the value of “VHCL/S SE·MTR ”.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. CHECK COMBINATION METERS
Check combination meter. Refer to DI-17, "
How to Proceed With Trouble Diagnosis" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 3 2 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 5.
5. 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 6.
NG >> Repair or replace damaged parts.
6. 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 (Approx.)(km/h)
VHCL/S SE ·MTR During driving Approximately matches the
speedometer reading.
SCIA2148E