INFINITI QX56 2004 Factory Service Manual

AT-140
DTC P1730 A/T INTERLOCK
Revision: August 20072004 QX56
Judgement of A/T InterlockUCS002FS
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 ProcedureUCS002FT
1. SELF-DIAGNOSIS
With CONSULT-II
1. Drive vehicle.
2. Stop vehicle and turn ignition switch “OFF”.
3. Turn ignition switch “ON”. (Do not start engine.)
4. Select “SELF-DIAG RESULTS” mode for “A/T” with CONSULT-
II.
OK or NG
OK >> GO TO 6.
NG >> Check low coast brake solenoid valve circuit and func-
tion. Refer to AT-169, "
DTC P1772 LOW COAST
BRAKE SOLENOID VALVE" , AT- 1 7 2 , "DTC P1774
LOW COAST BRAKE SOLENOID VALVE FUNCTION"
.
2. CHECK TCM
Perform TCM input/output signals inspection. Refer to AT- 9 0 , "
TCM Input/Output Signal Reference Values" .
OK or NG
OK >> GO TO 3.
NG >> GO TO 4.
3. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT-139, "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 5.
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 interlock
coupling pat-
tern3rd – 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
BCIA0031E

DTC P1730 A/T INTERLOCK
AT-141
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Revision: August 20072004 QX56
4. DETECT MALFUNCTIONING ITEM
Check the following items:

Power supply and ground circuit for TCM.

The A/T assembly harness connector pin terminals for damage or loose connection with harness connec-
tor.
OK or NG
OK >> GO TO 6.
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 4 1 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
6. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT- 1 3 9 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.

AT-142
DTC P1731 A/T 1ST ENGINE BRAKING
Revision: August 20072004 QX56
DTC P1731 A/T 1ST ENGINE BRAKINGPFP:00000
DescriptionUCS002FU
Fail-safe function to prevent sudden decrease in speed by engine brake other than at M1 position.
CONSULT-II Reference ValueUCS002FV
On Board Diagnosis LogicUCS002FW

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

Diagnostic trouble code “A/T 1ST E/BRAKING” with CONSULT-II is detected under the following condi-
tions.
–When TCM does not receive the proper voltage signal from the sensor.
–When TCM monitors each ATF pressure switch and solenoid monitor value, and detects as irregular when
engine brake of 1st gear acts other than at 1 position.
Possible CauseUCS002FX

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

Low coast brake solenoid valve

ATF pressure switch 2
DTC Confirmation ProcedureUCS002FY
NOTE:
If “DTC Confirmation Procedure” has been previously preformed, 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 2
consecutive seconds.
ENGINE SPEED: 1,200 rpm
Selector lever: “1” position
Gear position: 1st gear
5. If DTC is detected, go to AT-143, "
Diagnostic Procedure" .
Item name Condition Display value (ON-OFF display)
ON OFF SOLLow coast brake engaged. Refer to AT- 2 1
. ON
Low coast brake disengaged. Refer to AT- 2 1
. OFF
ATF PRES SW 2Low coast brake engaged. Refer to AT- 2 1
. ON
Low coast brake disengaged. Refer to AT- 2 1
. OFF
BCIA0030E

DTC P1731 A/T 1ST ENGINE BRAKING
AT-143
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Revision: August 20072004 QX56
Diagnostic ProcedureUCS002FZ
1. CHECK INPUT SIGNALS
With CONSULT-II
1. Start the engine.
2. Select “ECU INPUT SIGNALS” or “MAIN SIGNALS” in “DATA
MONITOR” mode for “A/T” with CONSULT-II.
3. Drive vehicle in the “M” position (1st gear), and confirm the ON/
OFF actuation of the “ATF PRES SW 2”.
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 2 , "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.
5. DETECT MALFUNCTIONING ITEM
Check the following items:

Power supply and ground circuit for TCM.

The A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> GO TO 6.
NG >> Repair or replace damaged parts.
Item name Condition Display value
(ON-OFF display)
ON OFF
SOLLow coast brake engaged. Refer to AT- 2 1
.ON
Low coast brake disengaged. Refer to AT- 2 1
.OFF
ATF PRES
SW 2Low coast brake engaged. Refer to AT- 2 1
.ON
Low coast brake disengaged. Refer to AT- 2 1
.OFF
PCIA0067E

AT-144
DTC P1731 A/T 1ST ENGINE BRAKING
Revision: August 20072004 QX56
6. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT-142, "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.

DTC P1752 INPUT CLUTCH SOLENOID VALVE
AT-145
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Revision: August 20072004 QX56
DTC P1752 INPUT CLUTCH SOLENOID VALVEPFP:31940
DescriptionUCS002G0
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 ValueUCS002G1
On Board Diagnosis LogicUCS002G2

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “I/C SOLENOID/CIRC” with CONSULT-II or P1752 without 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 CauseUCS002G3

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

Input clutch solenoid valve
DTC Confirmation ProcedureUCS002G4
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 6 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value (Approx) (A)
I/C SOLENOIDInput clutch disengaged. Refer to AT- 2 1
. 0.6 - 0.8
Input clutch engaged. Refer to AT- 2 1
. 0 - 0.05
BCIA0030E

AT-146
DTC P1752 INPUT CLUTCH SOLENOID VALVE
Revision: August 20072004 QX56
Diagnostic ProcedureUCS002G5
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “MAIN SIGNALS” in “DATA MONITOR” mode for “A/T”
with CONSULT-II.
3. Start the engine.
4. Read out the value of “I/C SOLENOID” while driving.
OK or NG
OK >> GO TO 6.
NG >> GO TO 2.
2. CHECK TCM
Perform TCM input/output signals inspection. Refer to AT- 9 0 , "
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-145, "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-241, "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
5. DETECT MALFUNCTIONING ITEM
Check the following items:

Power supply and ground circuit for TCM.

The A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> GO TO 6.
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
SCIA4793E

DTC P1752 INPUT CLUTCH SOLENOID VALVE
AT-147
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Revision: August 20072004 QX56
6. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT- 1 4 5 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.

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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Revision: August 20072004 QX56
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