engine INFINITI QX56 2010 Factory Service Manual

TM-92
< COMPONENT DIAGNOSIS >
P1774 LOW COAST BRAKE SOLENOID
P1774 LOW COAST BRAKE SOLENOID
DescriptionINFOID:0000000005148672
• Low coast brake solenoid valve is turned “ON” or “OFF” by the TCM in response to signals sent from the
transmission rang switch, output speed sensor and accelerator pedal 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 malfunc- tion such as control valve sticking, improper solenoid valve operation.
CONSULT-III Reference Value in Data Monitor ModeINFOID:0000000005148673
On Board Diagn osis LogicINFOID:0000000005148674
• This is an OBD-II self-diagnostic item.
• Diagnostic trouble code “P1774 L C BRAKE SOLENOID” with CONSULT-III 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 2 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 2 is irregular
during releasing accelerator pedal. (Other than during shift change)
Possible CauseINFOID:0000000005148675
• Harness or connectors (The solenoid and switch circuits are open or shorted.)
• Low coast brake solenoid valve
• ATF pressure switch 2
DTC Confirmation ProcedureINFOID:0000000005148676
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 proc edure to confirm the malfunction is eliminated.
WITH CONSULT-III
1. Start engine.
2. Accelerate vehicle to maintain the following conditions.
SLCT LVR POSI: “1” or “2” position
GEAR: “1st” or “2nd” (LC/B ON/OFF)
3. Perform step “2” again.
4. Turn ignition switch “OFF”, then perform step “1” to “3” again.
5. Check “SELF-DIAG RESULTS” mode for “TRANSMISSION” with CONSULT-III. If DTC (P1774) is detected, refer to TM-93, "
Diagnosis Procedure".
If DTC (P1772) is detected, go to TM-90, "
Diagnosis Procedure".
WITH GST
Follow the procedure “With CONSULT-III”.
Item name Condition Display value
ON OFF SOL Low coast brake engaged. Refer to
TM-9
.O N
Low coast brake disengaged. Refer to TM-9
.O FF
ATF PRES SW 2 Low coast brake engaged. Refer to
TM-9
.O N
Low coast brake disengaged. Refer to TM-9
.O FF
Revision: April 20092010 QX56

P1774 LOW COAST BRAKE SOLENOIDTM-93
< COMPONENT DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
Diagnosis ProcedureINFOID:0000000005148677
1.CHECK INPUT SIGNALS
With CONSULT-III
1. Start the engine.
2. Select “SELECTION FROM MENU” in “DATA MONI TOR” mode for “TRANSMISSION” with CONSULT-III.
3. Drive vehicle in the “1” or “2” position (“1
1” or “22” gear) and confirm the ON/OFF actuation of the “ATF
PRES SW 2” and “ON OFF SOL”.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to TM-94, "
Diagnosis Procedure".
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 connector.
OK or NG
OK >> Replace the control valve with TCM. Refer to TM-172, "Control Valve with TCM and A/T Fluid
Temperature Sensor 2 and Plug".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to TM-92, "
DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ON OFF SOL Low coast brake engaged. Refer to
TM-9
.O N
Low coast brake disengaged. Refer to TM-9
.O FF
ATF PRES SW 2 Low coast brake engaged. Refer to
TM-9
.O N
Low coast brake disengaged. Refer to TM-9
.O FF
Revision: April 20092010 QX56

TM-94
< COMPONENT DIAGNOSIS >
MAIN POWER SUPPLY AND GROUND CIRCUIT
MAIN POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000005148678
1.CHECK TCM POWER SOURCE STEP 1
1. Turn ignition switch OFF.
2. Disconnect A/T assembly harness connector.
3. Check voltage between A/T assembly harness connector termi- nals and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2.CHECK TCM POWER SOURCE STEP 2
1. Disconnect A/T assembly harness connector.
2. Turn ignition switch ON. (Do not start engine.)
3. Check voltage between A/T assembly harness connector termi- nals and ground.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING ITEM
Check the following items:
• Harness for short or open between battery and A/T assembly harness connector terminals 1, 2
• Harness for short or open between ignition switch and A/T assembly harness connector terminal 6
• 10A fuse [No. 3, 4, located in the fuse block (J /B)] and 10A fuse (No. 49, located in the IPDM E/R)
• Ignition switch
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
4.CHECK TCM GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/T assembly harness connector.
3. Check continuity between A/T assembly harness connector F9 terminals 5, 10 and ground.
If OK, check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
Item Connector TerminalVoltage
TCM F91 - Ground
Battery voltage
2 - Ground
6 - Ground 0V
SCIA2104E
ItemConnector TerminalVoltage
TCM F91 - Ground
Battery voltage
2 - Ground
6 - Ground
SCIA2105E
Continuity should exist.
SCIA2106E
Revision: April 20092010 QX56

TM-96
< COMPONENT DIAGNOSIS >
CLOSED THROTTLE POSITION AND WIDE OPEN THROTTLE POSITION CIR-
CUIT
CLOSED THROTTLE POSITION AND WIDE OPEN THROTTLE POSITION
CIRCUIT
CONSULT-III Reference Value in Data Monitor ModeINFOID:0000000005148679
Diagnosis ProcedureINFOID:0000000005148680
1.CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to TM-40.
NO >> GO TO 2.
2.CHECK THROTTLE POSI TION SIGNAL CIRCUIT
With CONSULT-III
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “ECU INPUT SIGNALS” in “DATA MONI TOR” mode for “TRANSMISSION” with CONSULT-III.
3. Depress accelerator pedal and read out the value of “CLSD THL POS” and “W/O THL POS”.
OK or NG
OK >> INSPECTION END
NG >> Check the following items. If NG, repair or replace damaged parts. • Perform the self-diagnosis for “ENGINE” with CONSULT-III.
• Open circuit or short to ground or shor t to power in harness or connectors.
• Pin terminals for damage or loos e connection with harness connector.
Item name Condition Display value
CLSD THL POS Released accelerator pedal.
ON
Fully depressed accelerator pedal. OFF
W/O THL POS Fully depressed accelerator pedal.
ON
Released accelerator pedal. OFF
Accelerator Pedal OperationMonitor Item
CLSD THL POS W/O THL POS
Released ONOFF
Fully depressed OFFON
Revision: April 20092010 QX56

BRAKE SIGNAL CIRCUITTM-97
< COMPONENT DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
BRAKE SIGNAL CIRCUIT
CONSULT-III Reference Val ue in Data Monitor ModeINFOID:0000000005148681
Diagnosis ProcedureINFOID:0000000005148682
1.CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to TM-40, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK STOP LAMP SWITCH CIRCUIT
With CONSULT-III
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “ECU INPUT SIGNALS” in “DATA MONITO R” mode for “TRANSMISSION” with CONSULT-III.
3. Read out ON/OFF switching action of the “BRAKESW”.
OK or NG
OK >> INSPECTION END
NG >> GO TO 3.
3.CHECK STOP LAMP SWITCH
Check continuity between stop lamp switch terminals 1 and 2.
Check stop lamp switch after adjusting brake pedal — refer to
BR-15, "
Inspection and Adjustment".
OK or NG
OK >> Check stop lamp switch circuit.
NG >> Repair or replace stop lamp switch.
Item name Condition Display value
BRAKESW Depressed brake pedal.
ON
Released brake pedal. OFF
ConditionContinuity
When brake pedal is depressed. Yes
When brake pedal is released. No
AWDIA0165ZZ
Revision: April 20092010 QX56

TM-98
< COMPONENT DIAGNOSIS >
TOW MODE SWITCH
TOW MODE SWITCH
DescriptionINFOID:0000000005148683
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.
Diagnosis ProcedureINFOID:0000000005148684
1.CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Is any malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to TM-40.
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 M258 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 terminals 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 connec- tor 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.
5.CHECK COMBINATION METER
Check the combination meter. Refer to MWI-4, "
Work Flow".
OK or NG
OK >> INSPECTION END
NO >> Repair or replace damaged parts.
Condition To w m o d e
switch Data (Approx.)
When ignition switch is turned to “ON” ON
0V
OFF Battery voltage
SCIA5156E
Condition Continuity
Tow mode switch “ON” Yes
Tow mode switch “OFF” No
SCIA5584E
Revision: April 20092010 QX56

TM-106
< ECU DIAGNOSIS >
TCM
ECU DIAGNOSIS
TCM
Reference ValueINFOID:0000000005148688
REFERENCE VALUES
NOTICE:
1. The CONSULT-III electrically displays shift timing and lock-up timing (that is, operation timing of eachsolenoid).
Check for time difference between actual shift timi ng and the CONSULT-III display. If the difference is
noticeable, mechanical parts (except solenoids, sens ors, etc.) may be malfunctioning. Check mechanical
parts using applicable diagnostic procedures.
2. Shift schedule (which implies gear position) display ed on CONSULT-III 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-III indicates the point where shifts are completed.
3. Display of solenoid valves on CONSULT-III changes at t he start of shifting, while gear position is displayed
upon completion of shifting (which is computed by TCM).
Item name Condition Display value (Approx.)
AT F T E M P S E 1 0°C (32 ° F) - 20 °C (68 °F) - 80 °C (176 °F) 3.3 - 2.7 - 0.9 V
TCC SOLENOID When perform slip lock-up.
0.2 - 0.4 A
When perform lock-up. 0.4 - 0.6 A
SLCT LVR POSI Selector 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
INPUT SPEED During driving (lock-up ON) Approximately matches the en-
gine speed.
VHCL/S SE-MTR During driving Approximately matches the
speedometer reading.
ATF PRES SW 2 Low coast brake engaged. Refer to
TM-9
.ON
Low coast brake disengaged. Refer to TM-9
.OFF
I/C SOLENOID Input clutch disengaged. Refer to
TM-9
.0.6 - 0 .8 A
Input clutch engaged. Refer to TM-9
.0 - 0 .0 5 A
FR/B SOLENOID Front brake engaged. Refer to
TM-9
.0 .6 - 0 .8 A
Front brake disengaged. Refer to TM-9
.0 - 0 .0 5 A
D/C SOLENOID Direct clutch disengaged. Refer to
TM-9
.0.6 - 0 .8 A
Direct clutch engaged. Refer to TM-9
.0 - 0 .0 5 A
HLR/C SOL High and low reverse clutch disengaged. Refer to
TM-9
.0.6 - 0 .8 A
High and low reverse clutch engaged. Refer to TM-9
.0 - 0 .0 5 A
Revision: April 20092010 QX56

TM-118
< ECU DIAGNOSIS >
TCM
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. Therefore, the customer's v ehicle has returned to normal, so handle according to the
“diagnostics flow” (Refer to TM-5, "
Work Flow").
FAIL-SAFE FUNCTION
If any malfunction occurs in a sensor or solenoid, th is function controls the A/T to mark driving possible.
Output Speed Sensor
• Signals are input from two systems - from output speed sensor installed on the transmission and from com-
bination meter so normal driving is possible even if there is a malfunction in one of the systems. And if output
speed sensor has unusual cases, 5GR is prohibited.
Accelerator Peda l Position Sensor
• If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM according
to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow sys-
tems, 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 according
to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow sys-
tems, 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.
Transmission Range Switch
• In the unlikely event that a malfunction signal enters t he 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” position to make driving possible.
Starter Relay
• The starter relay is switched “OFF”. (Starter starting is disabled.)
Interlock
• If there is an interlock judgment malfunction, the trans mission is fixed in 2GR to make driving possible.
NOTE:
When the vehicle is driven fixed in 2GR, a input speed sensor malfunction is displayed, but this is
not a input speed sensor malfunction.
• When the interlock is detected at the 3GR or more, it is locked at the 2GR.
1st Engine Braking
• When there is an 1st 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 driv- ing 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 isnot applied in 1GR and 2GR.
Input Clutch Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4GR 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 4GR 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 5GR; if the solenoid is OFF, 4GR.
Revision: April 20092010 QX56

TCM
TM-119
< ECU DIAGNOSIS >
C EF
G H
I
J
K L
M A
B
TM
N
O P
High and Low Revers
e Clutch Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4GR to make driving possible.
Input Speed Sensor 1 or 2
• The control is the same as if there were no input speed sensors, 5GR is prohibited.
DTC Inspection Priority ChartINFOID:0000000005148691
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 pe rform the trouble diagnosis for DTC U1000. Refer to
TM-40, "
Diagnosis Procedure".
DTC No. IndexINFOID:0000000005148692
NOTE:
If DTC U1000 is displayed with other DTC, first pe rform the trouble diagnosis for DTC U1000. Refer to
TM-40, "
Diagnosis Procedure".
Priority Detected items (DTC)
1 U1000 CAN COMM CIRCUIT
2 Except above
DTC
Items
(CONSULT- III screen terms) Reference
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only
“TRANSMISSION”
— P0615STARTER RELAY TM-41
P0700P0700TRANSMISSION CONTROL TM-44
P0705P0705T/M RANGE SWITCH A TM-45
P0710P1710FLUID TEMP SENSOR TM-73
P0717P0717INPUT SPEED SENSOR A TM-48
P0720P0720OUTPUT SPEED SENSOR TM-51
—P0725ENGINE SPEED TM-53
P0731P07311GR INCORRECT RATIO TM-56
P0732P07322GR INCORRECT RATIO TM-58
P0733P07333GR INCORRECT RATIO TM-60
P0734P07344GR INCORRECT RATIO TM-62
P0735P07355GR INCORRECT RATIO TM-64
P0740P0740TORQUE CONVERTER TM-65
P0744 P0744 TORQUE CONVERTER TM-68
P0745P0745PC SOLENOID A TM-69
—P1705TP SENSOR TM-71
—P1721VEHICLE SPEED SIGNAL TM-76
P1730P1730INTERLOCK TM-78
—P17311GR E/BRAKING TM-80
P1752P1752INPUT CLUTCH SOLENOID TM-82
P1757P1757FR BRAKE SOLENOID TM-84
P1762P1762DRCT CLUTCH SOLENOID TM-86
P1767P1767HLR CLUTCH SOLENOID TM-88
Revision: April 20092010 QX56

TM-120
< ECU DIAGNOSIS >
TCM
*1: These numbers are prescribed by SAE J2012.
*2: These malfunctions cannot be displayed MIL if another malfunction is assigned to MIL.
DTC Alphabetical IndexINFOID:0000000005148693
NOTE:
If DTC U1000 is displayed with other DTC, first perform the trouble diagnosis for DTC U1000. Refer to
TM-40, "
Diagnosis Procedure".
*1: These numbers are prescribed by SAE J2012.
*2: These malfunctions cannot be displayed MIL if another malfunction is assigned to MIL. P1772
P1772L C BRAKE SOLENOID TM-90
P1774 (2*) P1774 L C BRAKE SOLENOID TM-93
U1000U1000CAN COMM CIRCUIT TM-40
DTC
Items
(CONSULT- III screen terms) Reference
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only
“TRANSMISSION”
Items
(CONSULT- III screen terms) DTC
Reference
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only “TRANS-
MISSION”
1ST E/BRAKING —P1731TM-80
1GR INCORRECT RATIO P0731P0731TM-56
2GR INCORRECT RATIO P0732P0732TM-58
3GR INCORRECT RATIO P0733P0733TM-60
4GR INCORRECT RATIO P0734P0734TM-62
5GR INCORRECT RATIO P0735P0735TM-64
INTERLOCK P1730P1730TM-78
TORQUE CONVERTER P0744 P0744 TM-68
FLUID TEMP SENSOR P0710P1710TM-73
CAN COMM CIRCUIT U1000U1000TM-40
DRCT CLUTCH SOLENOID P1762P1762 TM-86
ENGINE SPEED —P0725TM-53
FR BRAKE SOLENOID P1757P1757TM-84
HLR CLUTCH SOLENOID P1767P1767TM-88
INPUT CLUTCH SOLENOID P1752P1752TM-82
PC SOLENOID A P0745P0745TM-69
L C BRAKE SOLENOID P1772P1772TM-90
L C BRAKE SOLENOID P1774 P1774 TM-93
T/M RANGE SWITCH A P0705P0705TM-45
STARTER RELAY —P0615TM-41
TORQUE CONVERTER P0740P0740TM-65
TRANSMISSION CONTROL P0700P0700TM-44
TP SENSOR —P1705TM-71
INPUT SPEED SENSOR A P0717P0717TM-48
VEHICLE SPEED SIGNAL —P1721TM-76
OUTPUT SPEED SENSOR P0720P0720TM-51
Revision: April 20092010 QX56