ignition INFINITI QX56 2008 Factory Service Manual

TM-90
< COMPONENT DIAGNOSIS >
P1774 LOW COAST BRAKE SOLENOID
P1774 LOW COAST BRAKE SOLENOID
DescriptionINFOID:0000000001604154
• Low coast brake solenoid valve is turned “ON” or “OFF” by the TCM in response to signals sent from the
transmission range switch, output speed sensor and accele rator pedal position sensor (throttle position sen-
sor). 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:0000000001604155
On Board Diagn osis LogicINFOID:0000000001604156
• This is an OBD-II self-diagnostic item.
• Diagnostic trouble code “P1774” 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:0000000001604157
• Harness or connectors
(The solenoid and switch circuits are open or shorted.)
• Low coast brake solenoid valve
• ATF pressure switch 2
DTC Confirmation ProcedureINFOID:0000000001604158
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.
Selector lever: “1” or “2” position
Gear position: “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-90, "
Diagnosis Procedure".
If DTC (P1772) is detected, go to TM-88, "
Diagnosis Procedure".
WITH GST
Follow the procedure “With CONSULT-III”.
Diagnosis ProcedureINFOID:0000000001604159
1.CHECK INPUT SIGNALS
Item nameCondition Display value
ON OFF SOL Low coast brake engaged. Refer to
TM-9
ON
Low coast brake disengaged. Refer to TM-9
OFF
ATF PRES SW 2 Low coast brake engaged. Refer to
TM-9
ON
Low coast brake disengaged. Refer to TM-9
OFF
Revision: March 2010 2008 QX56

TM-92
< COMPONENT DIAGNOSIS >
MAIN POWER SUPPLY AND GROUND CIRCUIT
MAIN POWER SUPPLY AND GROUND CIRCUIT
Diagnosis ProcedureINFOID:0000000001604160
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, 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: March 2010 2008 QX56

TM-94
< 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:0000000001604161
Diagnosis ProcedureINFOID:0000000001604162
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-38.
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 nameCondition 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: March 2010 2008 QX56

BRAKE SIGNAL CIRCUITTM-95
< 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:0000000001604163
Diagnosis ProcedureINFOID:0000000001604164
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-38, "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 “BRAKE SW”.
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
BRAKE SW Depressed brake pedal.
ON
Released brake pedal. OFF
ConditionContinuity
When brake pedal is depressed Yes
When brake pedal is released No
AWDIA0165ZZ
Revision: March 2010 2008 QX56

TM-96
< COMPONENT DIAGNOSIS >
TOW MODE SWITCH
TOW MODE SWITCH
DescriptionINFOID:0000000001604165
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:0000000001604167
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-38.
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: March 2010 2008 QX56

TM-100
< COMPONENT DIAGNOSIS >
A/T SHIFT LOCK SYSTEM
Terminals And Reference Values
INFOID:0000000001604171
SHIFT LOCK HARNESS CONNECTOR TERMINALS LAYOUT
SHIFT LOCK CONTROL UNIT INSPECTION TABLE
Data are reference values.
NOTE:
Confirm that the pointer swings only momentarily because the output time is so short. If the inspection is done with an oscillo scope, it
should be observed that the power source voltage lasts for 3.5 to 10 ms.
Component DescriptionINFOID:0000000001604172
SHIFT LOCK SOLENOID
AWDIA0043ZZ
TER-
MINAL NO. WIRE
COLOR ITEM
CONDITION VOLTAGE
(Approx.)
1Y/RPower source Ignition switch: “ON”
Battery voltage
Ignition switch: “OFF” Battery voltage
2 L/R Detent switch (key) Selector lever in “P” position
0V
Except above with ignition knob switch in “PUSHED” or “ON”
position Battery voltage
3GRDetent switch Selector lever in “P” position
0V
Except above Battery voltage
4 R/G Stop lamp switch Brake pedal applied
Battery voltage
Brake pedal released 0V
5 W/R Vehicle speed signal ——
6 G/R Ignition signal Ignition switch: “ON”
Battery voltage
Ignition switch: “OFF” 0V
7 R/W Shift lock solenoid Brake pedal applied with ignition knob switch in “ON” position 0V
Except above
Battery voltage
8 B Ground ——
9 R Key lock solenoid Selector lever in any position except “P”, and ignition knob
switch turned from “ON” to “OFF”
Battery voltage for ap-
prox. 0.1 sec. (Note)
Except above 0V
10 W/G Key unlock solenoid Ignition knob switch in “PUSHED” position.
Battery voltage for ap-
prox. 0.1 sec. (Note)
Except above 0V
Revision: March 2010 2008 QX56

TM-102
< COMPONENT DIAGNOSIS >
A/T SHIFT LOCK SYSTEM
• Check operation by applying battery voltage to key switch and igni-tion knob switch terminal 5 and ground to terminal 6.
CAUTION:
Be careful not to cause burnout of the component.
IGNITION KNOB SWITCH
• Check continuity between terminals of the key switch and ignition
knob switch.
STOP LAMP SWITCH
• Check continuity between stop lamp switch terminals 1 and 2.
Check stop lamp switch after adjusting brake pedal.
AWDIA0545ZZ
Condition Terminal No. Continuity
Switch pushed 1 - 2Ye s
Switch released No
AWDIA0546ZZ
ConditionTerminal No. Continuity
When brake pedal is depressed 1 -2Ye s
When brake pedal is released No
AWDIA0165ZZ
Revision: March 2010 2008 QX56

TCM
TM-115
< ECU DIAGNOSIS >
C EF
G H
I
J
K L
M A
B
TM
N
O P
Even when the electronic circuits are normal, under s pecial 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 vehicle 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 s peed sensor installed on the transmission and from com-
bination meter so normal driving is possible even if t here is a malfunction in one of the systems. And if output
speed sensor has unusual cases, 5GR is prohibited.
Accelerator Pedal 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” range 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 tr ansmission is fixed in 2GR to make driving possible.
NOTE:
When the vehicle is driven fixed in 2GR, a inpu t 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 is
not 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 4th gear 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: March 2010 2008 QX56

TM-118
< SYMPTOM DIAGNOSIS >
SYSTEM SYMPTOM
SYMPTOM DIAGNOSIS
SYSTEM SYMPTOM
A/T Check Indicator Lamp Does Not Come OnINFOID:0000000001604179
SYMPTOM:
AT CHECK indicator lamp does not come on for about 2 seconds when turning ignition switch to
“ON”.
DIAGNOSTIC PROCEDURE
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-21, "CAN Communication".
NO >> GO TO 2.
2.CHECK A/T CHECK INDICATOR LAMP CIRCUIT
Check the combination meter. Refer to MWI-19, "
WARNING LAMPS/INDICATOR LAMPS : System Descrip-
tion".
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3.CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to TM-92, "
Diagnosis Procedure".
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
Engine Cannot Be Started in "P" or "N" PositionINFOID:0000000001604180
SYMPTOM:
•Engine cannot be started with select or lever in “P” or “N” position.
• Engine can be started with selector lever in “D”or “R” position.
DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSIS RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnosis results indicate transmission range switch?
YES >> Check the malfunctioning system. Refer to TM-43, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK CONTROL CABLE
Check the control cable.
• Refer to TM-194, "
Checking of A/T Position".
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to TM-194, "
Adjustment of A/
T Position".
3.CHECK STARTING SYSTEM
LCIA0345E
Revision: March 2010 2008 QX56

SYSTEM SYMPTOMTM-121
< SYMPTOM DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
Large Shock("N" to "D" Position)INFOID:0000000001604183
SYMPTOM:
A noticeable shock occurs when the selector lever is shifted from the “N” to “D” position.
DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnostic results indicate A/T fluid temperature sensor, engine speed signal, accelerator pedal
position sensor, front brake solenoid valve, CAN communication line?
YES >> Check the malfunctioning system. Refer to TM-71, "Diagnosis Procedure", TM-51, "Diagnosis
Procedure", TM-69, "Diagnosis Procedure", TM-82, "Diagnosis Procedure", TM-38, "Diagnosis
Procedure".
NO >> GO TO 2.
2.ENGINE IDLE SPEED
Check the engine idle speed. Refer to EC-17, "
Idle Speed and Ignition Timing Check".
OK or NG
OK >> GO TO 3.
NG >> Repair.
3.CHECK CONTROL CABLE
Check the control cable.
• Refer to TM-194, "
Checking of A/T Position".
OK or NG
OK >> GO TO 4.
NG >> Adjust control cable. Refer to TM-194, "
Adjustment of A/
T Position".
4.CHECK A/T FLUID LEVEL
Check the A/T fluid level. Refer to TM-178, "
Checking the A/T Fluid
(ATF)".
OK or NG
OK >> GO TO 5.
NG >> Refill ATF.
5.CHECK LINE PRESSURE
LCIA0345E
SAT638A
Revision: March 2010 2008 QX56