2004 INFINITI QX56 tow

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Revision: August 20072004 QX56 On Board Diagnosis Logic ................................... 151
Possible Cause .................................................... 151
DTC Confirmation Procedure ............................... 151
Diagnostic Procedure ........................................... 152
DTC P1759 FRONT BRAKE SOLENOID VALVE
FUNCTION .............................................................. 154
Description ........................................................... 154
CONSULT-II Reference Value .............................. 154
On Board Diagnosis Logic ................................... 154
Possible Cause .................................................... 154
DTC Confirmation Procedure ............................... 154
Diagnostic Procedure ........................................... 155
DTC P1762 DIRECT CLUTCH SOLENOID VALVE . 157
Description ........................................................... 157
CONSULT-II Reference Value .............................. 157
On Board Diagnosis Logic ................................... 157
Possible Cause .................................................... 157
DTC Confirmation Procedure ............................... 157
Diagnostic Procedure ........................................... 158
DTC P1764 DIRECT CLUTCH SOLENOID VALVE
FUNCTION .............................................................. 160
Description ........................................................... 160
CONSULT-II Reference Value .............................. 160
On Board Diagnosis Logic ................................... 160
Possible Cause .................................................... 160
DTC Confirmation Procedure ............................... 160
Diagnostic Procedure ........................................... 161
DTC P1767 HIGH AND LOW REVERSE CLUTCH
SOLENOID VALVE ................................................. 163
Description ........................................................... 163
CONSULT-II Reference Value .............................. 163
On Board Diagnosis Logic ................................... 163
Possible Cause .................................................... 163
DTC Confirmation Procedure ............................... 163
Diagnostic Procedure ........................................... 164
DTC P1769 HIGH AND LOW REVERSE CLUTCH
SOLENOID VALVE FUNCTION ............................. 166
Description ........................................................... 166
CONSULT-II Reference Value .............................. 166
On Board Diagnosis Logic ................................... 166
Possible Cause .................................................... 166
DTC Confirmation Procedure ............................... 166
Diagnostic Procedure ........................................... 167
DTC P1772 LOW COAST BRAKE SOLENOID
VALVE ..................................................................... 169
Description ........................................................... 169
CONSULT-II Reference Value .............................. 169
On Board Diagnosis Logic ................................... 169
Possible Cause .................................................... 169
DTC Confirmation Procedure ............................... 169
Diagnostic Procedure ........................................... 170
DTC P1774 LOW COAST BRAKE SOLENOID
VALVE FUNCTION ................................................. 172
Description ........................................................... 172
CONSULT-II Reference Value .............................. 172
On Board Diagnosis Logic ................................... 172
Possible Cause .................................................... 172
DTC Confirmation Procedure ............................... 172
Diagnostic Procedure ........................................... 173DTC P1841 ATF PRESSURE SWITCH 1 ...............175
Description ............................................................175
CONSULT-II Reference Value ..............................175
On Board Diagnosis Logic ....................................175
Possible Cause .....................................................175
DTC Confirmation Procedure ...............................175
Diagnostic Procedure ...........................................176
DTC P1843 ATF PRESSURE SWITCH 3 ...............178
Description ............................................................178
CONSULT-II Reference Value ..............................178
On Board Diagnosis Logic ....................................178
Possible Cause .....................................................178
DTC Confirmation Procedure ...............................178
Diagnostic Procedure ...........................................179
DTC P1845 ATF PRESSURE SWITCH 5 ...............181
Description ............................................................181
CONSULT-II Reference Value ..............................181
On Board Diagnosis Logic ....................................181
Possible Cause .....................................................181
DTC Confirmation Procedure ...............................181
Diagnostic Procedure ...........................................182
DTC P1846 ATF PRESSURE SWITCH 6 ...............184
Description ............................................................184
CONSULT-II Reference Value ..............................184
On Board Diagnosis Logic ....................................184
Possible Cause .....................................................184
DTC Confirmation Procedure ...............................184
Diagnostic Procedure ...........................................185
CLOSED THROTTLE POSITION AND WIDE OPEN
THROTTLE POSITION CIRCUIT ............................187
CONSULT-II Reference Value ..............................187
Diagnostic Procedure ...........................................187
BRAKE SIGNAL CIRCUIT ......................................188
CONSULT-II Reference Value ..............................188
Diagnostic Procedure ...........................................188
TOW MODE SWITCH .............................................189
Description ............................................................189
Diagnostic Procedure ...........................................189
TROUBLE DIAGNOSIS FOR SYMPTOMS ............191
AT CHECK Indicator Lamp Does Not Come On ..191
Engine Cannot Be Started In “P” or “N” Position ..192
In “P” Position, Vehicle Moves When Pushed ......193
In “N” Position, Vehicle Moves ..............................194
Large Shock (“N” to “D” Position) .........................195
Vehicle Does Not Creep Backward In “R” Position .198
Vehicle Does Not Creep Forward In “D” Position . 201
Vehicle Cannot Be Started From D
1 .....................203
A/T Does Not Shift: D
1 → D2 ................................206
A/T Does Not Shift: D
2 → D3 ................................208
A/T Does Not Shift: D
3 → D4 ................................210
A/T Does Not Shift: D
4 → D5 ................................213
A/T Does Not Perform Lock-up ............................215
A/T Does Not Hold Lock-up Condition ..................217
Lock-up Is Not Released ......................................219
Engine Speed Does Not Return to Idle ................220
A/T Does Not Shift: 5th gear → 4th gear ..............221
A/T Does Not Shift: 4th gear → 3rd gear ..............224
A/T Does Not Shift: 3rd gear → 2nd gear .............225

AT-8
PRECAUTIONS
Revision: August 20072004 QX56
Precautions UCS002C3

Before connecting or disconnecting the A/T assembly har-
ness connector, turn ignition switch “OFF” and disconnect
negative battery cable. Because battery voltage is applied
to TCM even if ignition switch is turned “OFF”.

After performing each TROUBLE DIAGNOSIS, perform
“DTC (Diagnostic Trouble Code) CONFIRMATION PROCE-
DURE”.
If the repair is completed the DTC should not be displayed
in the “DTC CONFIRMATION PROCEDURE”.

Always use the specified brand of ATF. Refer to MA-10, "RECOMMENDED FLUIDS AND LUBRICANTS"
.

Use paper rags not cloth rags during work.

After replacing the ATF, dispose of the waste oil using the methods prescribed by law, ordinance, etc.

Before proceeding with disassembly, thoroughly clean the outside of the transaxle. It is important to pre-
vent the internal parts from becoming contaminated by dirt or other foreign matter.

Disassembly should be done in a clean work area.

Use lint-free cloth or towels for wiping parts clean. Common shop rags can leave fibers that could interfere
with the operation of the transaxle.

Place disassembled parts in order for easier and proper assembly.

All parts should be carefully cleaned with a general purpose, non-flammable solvent before inspection or
reassembly.

Gaskets, seals and O-rings should be replaced any time the transaxle is disassembled.

It is very important to perform functional tests whenever they are indicated.

The valve body contains precision parts and requires extreme care when parts are removed and serviced.
Place disassembled valve body parts in order for easier and proper assembly. Care will also prevent
springs and small parts from becoming scattered or lost.

Properly installed valves, sleeves, plugs, etc. will slide along bores in valve body under their own weight.

Before assembly, apply a coat of recommended ATF to all parts. Apply petroleum jelly to protect O-rings
and seals, or hold bearings and washers in place during assembly. Do not use grease.

Extreme care should be taken to avoid damage to O-rings, seals and gaskets when assembling.

After overhaul, refill the transaxle with new ATF.

When the A/T drain plug is removed, only some of the fluid is drained. Old A/T fluid will remain in torque
converter and ATF cooling system.
Always follow the procedures under “Changing A/T Fluid” in the AT section when changing A/T fluid. Refer
to AT-13, "
Changing A/T Fluid" , AT- 1 3 , "Checking A/T Fluid" .
SEF 2 89 H
SEF 2 17 U

A/T FLUID
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Revision: August 20072004 QX56
A/T Fluid Cooler CleaningUCS002CA
Whenever an automatic transmission is repaired, overhauled, or replaced, the A/T fluid cooler mounted in the
radiator must be inspected and cleaned.
Metal debris and friction material, if present, can become trapped in the A/T fluid cooler. This debris can con-
taminate the newly serviced A/T or, in severe cases, can block or restrict the flow of A/T fluid. In either case,
malfunction of the newly serviced A/T may result.
Debris, if present, may build up as A/T fluid enters the cooler inlet. It will be necessary to back flush the cooler
through the cooler outlet in order to flush out any built up debris.
A/T FLUID COOLER CLEANING PROCEDURE
1. Position an oil pan under the automatic transmission's inlet and outlet cooler hoses.
2. Identify the inlet and outlet fluid cooler hoses.
3. Disconnect the fluid cooler inlet and outlet rubber hoses from the
steel cooler tubes or bypass valve.
NOTE:
Replace the cooler hoses if rubber material from the hose
remains on the tube fitting.
4. Allow any A/T fluid that remains in the cooler hoses to drain into
the oil pan.
5. Insert the extension adapter hose of a can of Transmission
Cooler Cleaner (Nissan P/N 999MP-AM006) into the cooler out-
let hose.
CAUTION:

Wear safety glasses and rubber gloves when spraying
the Transmission Cooler Cleaner.

Spray cooler cleaner only with adequate ventilation.

Avoid contact with eyes and skin.

Do not breath vapors or spray mist.
6. Hold the hose and can as high as possible and spray Transmis-
sion Cooler Cleaner in a continuous stream into the cooler outlet
hose until fluid flows out of the cooler inlet hose for 5 seconds.
7. Insert the tip of an air gun into the end of the cooler outlet hose.
8. Wrap a shop rag around the air gun tip and of the cooler outlet
hose.
9. Blow compressed air regulated to 5 - 9 kg/cm
2 (70 - 130 psi) through the cooler outlet hose for 10 sec-
onds to force out any remaining fluid.
10. Repeat steps 5 through 9 three additional times.
11. Position an oil pan under the banjo bolts that connect the fluid cooler steel lines to the transmission.
12. Remove the banjo bolts.
13. Flush each steel line from the cooler side back toward the transmission by spraying Transmission Cooler
Cleaner in a continuous stream for 5 seconds.
SCIA3830E
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AT-16
A/T FLUID
Revision: August 20072004 QX56
14. Blow compressed air regulated to 5 - 9 kg/cm2 (70 - 130 psi) through each steel line from the cooler side
back toward the transmission for 10 seconds to force out any remaining fluid.
15. Ensure all debris is removed from the steel cooler lines.
16. Ensure all debris is removed from the banjo bolts and fittings.
17. PerformAT-16, "
A/T FLUID COOLER DIAGNOSIS PROCEDURE" .
A/T FLUID COOLER DIAGNOSIS PROCEDURE
NOTE:
Insufficient cleaning of the cooler inlet hose exterior may lead to inaccurate debris identification.
1. Position an oil pan under the automatic transmission's inlet and outlet cooler hoses.
2. Clean the exterior and tip of the cooler inlet hose.
3. Insert the extension adapter hose of a can of Transmission
Cooler Cleaner (Nissan P/N 999MP-AM006) into the cooler out-
let hose.
CAUTION:

Wear safety glasses and rubber gloves when spraying
the Transmission Cooler Cleaner.

Spray cooler cleaner only with adequate ventilation.

Avoid contact with eyes and skin.

Do not breath vapors or spray mist.
4. Hold the hose and can as high as possible and spray Transmis-
sion Cooler Cleaner in a continuous stream into the cooler outlet
hose until fluid flows out of the cooler inlet hose for 5 seconds.
5. Tie a common white, basket-type coffee filter to the end of the
cooler inlet hose.
6. Insert the tip of an air gun into the end of the cooler outlet hose.
7. Wrap a shop rag around the air gun tip and end of cooler outlet
hose.
8. Blow compressed air regulated to 5 - 9 kg/cm
2 (70 - 130 psi)
through the cooler outlet hose to force any remaining A/T fluid
into the coffee filter.
9. Remove the coffee filter from the end of the cooler inlet hose.
10. Perform AT - 1 7 , "
A/T FLUID COOLER INSPECTION PROCE-
DURE" .
SCIA3831E
SCIA3833E
SCIA3834E

TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
TROUBLE DIAGNOSISPFP:00004
DTC Inspection Priority ChartUCS002C R
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC U1000 is displayed with other DTCs, first perform the trouble diagnosis for DTC U1000. Refer to
AT-1 03
.
Fail-SafeUCS002CS
The TCM has an electrical fail-safe mode. This mode makes it possible to operate even if there is a an error in
a main electronic control input/output signal circuit. In fail-safe mode the transmission is fixed in 2nd or 4th
(depending on the breakdown position), so the customer should feel “slipping” or “poor acceleration”. When
fail-safe mode is triggered, when the ignition switch is switched “ON”, the AT CHECK indicator lamp flashes for
about 8 seconds.
Even when the electronic circuits are normal, under special conditions (for example, when slamming on the
brake with the wheels spinning drastically and stopping the tire rotation), the transmission can go into fail-safe
mode. If this happens, switch “OFF” the ignition switch for 10 seconds, then switch it “ON” again to return to
the normal shift pattern. Also, the AT CHECK indicator lamp flashes for about 8 seconds once, then is cleared.
Therefore, the customer's vehicle has returned to normal, so handle according to the “diagnostics flow” (Refer
to AT-46, "
WORK FLOW" ).
FAI L-S AFE FUN CT ION
If any malfunction occurs in a sensor or solenoid, this function controls the A/T to mark driving possible.
Vehicle Speed Sensor

Signals are input from two systems - from vehicle speed sensor A/T (revolution sensor) installed on the
transmission and from combination meter so normal driving is possible even if there is a malfunction in
one of the systems. And if vehicle speed sensor A/T (revolution sensor) has unusual cases, 5th gear is
prohibited.
Accelerator Pedal Position Sensor

If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM accord-
ing to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow
systems, the engine speed is fixed by ECM to a pre-determined engine speed to make driving possible.
Throttle Position Sensor

If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM accord-
ing to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow
systems, the accelerator opening angle is controlled by the idle signal sent from the ECM which is based
on input indicating either idle condition or off-idle condition (pre-determined accelerator opening) in order
to make driving possible.
PNP Switch

In the unlikely event that a malfunction signal enters the TCM, the position indicator is switched “OFF”, the
starter relay is switched “OFF” (starter starting is disabled), the back-up lamp relay switched “OFF” (back-
up lamp is OFF) and the position is fixed to the “D” range to make driving possible.
Starter Relay

The starter relay is switched “OFF”. (Starter starting is disabled.)
Priority Detected items (DTC)
1 U1000 CAN communication line
2 Except above

TROUBLE DIAGNOSIS
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Vehicle Speed When Shifting GearsUCS002D3
NORMAL MODE

At half throttle, the accelerator opening is 4/8 of the full opening.
TOW MODE

At half throttle, the accelerator opening is 4/8 of the full opening.
Vehicle Speed When Performing and Releasing Complete Lock-up UCS002D4

At closed throttle, the accelerator opening is less than 1/8 condition.

At half throttle, the accelerator opening is 4/8 of the full opening.
Vehicle Speed When Performing and Releasing Slip Lock-upUCS002D5

At closed throttle, the accelerator opening is less than 1/8 condition. Final
gear
ratioThrottle positionVehicle speed km/h (MPH)
D
1 →D2D2 →D3D3 →D4D4 →D5D5 →D4D4 →D3D3 →D2D2 →D1
2.937Full throttle 70 - 74
(44 - 46)112 - 120
(70 - 75)176 - 186
(110 - 116)249 - 259
(155 - 161)245 - 255
(152 - 159)166 - 176
(103 - 110)100 - 108
(62 - 67)43 - 47
(27 - 30)
Half throttle 46 - 50
(28 - 31)74 - 82
(46 - 51)103 - 113
(64 - 70)135 - 145
(84 - 90)109 - 119
(68 - 74)69 - 79
(43 - 49)44 - 52
(27 - 32)11 - 1 5
(7 - 10)
3.357Full throttle 61 - 65
(38 - 41)97 - 105
(61 - 66)153 - 163
(95 - 102)236 - 246
(147 - 153)232 - 242
(144 - 151)143 - 153
(89 - 95)87 - 95
(54 - 59)43 - 47
(27 - 29)
Half throttle 41 - 45
(26 - 28)66 - 74
(41 - 46)89 - 99
(56 - 62)117 - 127
(73 - 79)95 - 105
(59 - 65)59 - 69
(37 - 43)38 - 46
(24 - 29)11 - 1 5
(7 - 10)
Final
gear
ratioThrottle positionVehicle speed km/h (MPH)
D
1 →D2D2 →D3D3 →D4D4 →D5D5 →D4D4 →D3D3 →D2D2 →D1
2.937Full throttle 70 - 74
(44 - 46)112 - 120
(70 - 75)176 - 186
(110 - 116)249 - 259
(155 - 161)245 - 255
(152 - 159)166 - 176
(103 - 110)100 - 108
(62 - 67)43 - 47
(27 - 30)
Half throttle 50 - 54
(31 - 34)81 - 89
(50 - 55)113 - 123
(70 - 76)135 - 145
(84 - 90)109 - 119
(68 - 74)68 - 78
(42 - 48)44 - 52
(27 - 32)11 - 1 5
(7 - 10)
3.357Full throttle 61 - 65
(38 - 41)97 - 105
(61 - 66)153 - 163
(95 - 102)236 - 246
(147 - 153)232 - 242
(144 - 151)143 - 153
(89 - 95)87 - 95
(54 - 59)43 - 47
(27 - 29)
Half throttle 43 - 47
(27 - 29)72 - 80
(45 - 50)98 - 108
(61 - 67)117 - 127
(73 - 79)95 - 105
(59 - 65)59 - 69
(37 - 43)37 - 45
(23 - 28)11 - 1 5
(7 - 10)
Final
gear
ratioThrottle positionVehicle speed km/h (MPH)
Lock-up “ON” Lock-up “OFF”
2.937Closed throttle 74 - 82 (46 - 51) 71 - 79 (45 - 49)
Half throttle 188 - 196 (117 - 122) 136 - 144 (85 - 90)
3.357Closed throttle 65 - 73 (41 - 46) 62 - 70 (39 - 44)
Half throttle 168 - 176 (105 - 110) 118 - 126 (74 - 79)
Final
gear
ratioThrottle position Gear positionVehicle speed km/h (MPH)
Slip lock-up “ON” Slip lock-up “OFF”
2.937 Closed throttle4th 52 - 60 (33 - 38) 49 - 57 (31 - 36)
5th 52 - 60 (33 - 38) 49 - 57 (31 - 36)
3.357 Closed throttle4th 46 - 54 (29 - 34) 43 - 51 (27 - 32)
5th 46 - 54 (29 - 34) 43 - 51 (27 - 32)

TOW MODE SWITCH
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Revision: August 20072004 QX56
TOW MODE SWITCHPFP:25129
DescriptionUCS002IG
When tow mode switch is “ON”, tow mode switch signals are sent to TCM from combination meter by CAN
communication line.Then it`s a tow mode condition.
Diagnostic ProcedureUCS002IH
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT - 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is any 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.
2. CHECK POWER SOURCE
1. Turn ignition switch “ON”. (Do not start engine.)
2. Check the voltage between tow mode switch connector terminal
1 and ground.
OK or NG
OK >>INSPECTION END
NG >> GO TO 3.
3. CHECK TOW MODE SWITCH
1. Turn ignition switch “OFF”.
2. Disconnect tow mode switch connector.
3. Check continuity between tow mode switch connector M254 ter-
minals 1 and 2.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace tow mode switch.
4. DETECT MALFUNCTIONING ITEM
Check the following items. If any items are damaged, repair or replace damaged parts.

Harness for short or open between combination meter connector terminal 35 and tow mode switch con-
nector terminal 1.

Harness for short or open between tow mode switch connector terminal 2 and ground.
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
ConditionTo w m o d e
switchData (Approx.)
When ignition switch is turned to “ON”ON 0V
OFF Battery voltage
SCIA5156E
Condition Continuity
To w m o d e s w i t c h “ O N ” Ye s
To w m o d e s w i t c h “ O F F ” N o
SCIA5157E

AT-190
TOW MODE SWITCH
Revision: August 20072004 QX56
5. CHECK COMBINATION METER
Check the combination meter. Refer to DI-17, "
How to Proceed With Trouble Diagnosis" .
OK or NG
OK >>INSPECTION END
NO >> Repair or replace damaged parts.