2007 INFINITI QX56 brake

DTC P1772 LOW COAST BRAKE SOLENOID VALVE
AT-147
< SERVICE INFORMATION >
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1. Turn ignition switch “ON”.
2. Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II.
3. Start the engine.
4. Read out the value of “ON OFF SOL” while driving.
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 AT-158
.
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 AT-210, "Control Valve with TCM and A/T Fluid Tem-
perature Sensor 2".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to AT-146, "
DTC Confirmation Procedure".
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ON OFF SOLLow coast brake engaged. Refer to AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
SCIA4794E

AT-148
< SERVICE INFORMATION >
DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
DescriptionINFOID:0000000003532408
• Low coast brake solenoid valve is turned “ON” or “OFF” 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.
• 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-II Reference Value in Data Monitor ModeINFOID:0000000003532409
On Board Diagnosis LogicINFOID:0000000003532410
• This is an OBD-II self-diagnostic item.
• Diagnostic trouble code “P1774 LC/B SOLENOID FNCT” with 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
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:0000000003532411
• Harness or connectors
(The solenoid and switch circuits are open or shorted.)
• Low coast brake solenoid valve
• ATF pressure switch 2
DTC Confirmation ProcedureINFOID:0000000003532412
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.
Selector lever: “1” or “2” position
Gear position: “1st” or “2nd” gear (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 “A/T” with CONSULT-
II. If DTC (P1774) is detected, refer to AT-149, "
Diagnosis Pro-
cedure".
If DTC (P1772) is detected, go to AT-146, "
Diagnosis Proce-
dure".
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value
ON OFF SOLLow coast brake engaged. Refer to AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
ATF PRES SW 2Low coast brake engaged. Refer to AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
BCIA0031E

DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
AT-149
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Diagnosis ProcedureINFOID:0000000003532413
1.CHECK INPUT SIGNALS
With CONSULT-II
1. Start the engine.
2. Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II.
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 AT-158
.
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 AT-210, "Control Valve with TCM and A/T Fluid Tem-
perature Sensor 2".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to AT-148, "
DTC Confirmation Procedure".
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ON OFF SOLLow coast brake engaged. Refer to AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
ATF PRES
SW 2Low coast brake engaged. Refer to AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
SCIA4794E

AT-150
< SERVICE INFORMATION >
DTC P1841 ATF PRESSURE SWITCH 1
DTC P1841 ATF PRESSURE SWITCH 1
DescriptionINFOID:0000000003532414
Fail-safe function to detect front brake clutch solenoid valve condition.
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000003532415
On Board Diagnosis LogicINFOID:0000000003532416
• This is not an OBD-II self-diagnostic item.
• Diagnostic trouble code “P1841 ATF PRES SW 1/CIRC” with CONSULT-II is detected when TCM detects
that actual gear ratio is normal, and relation between gear position and condition of ATF pressure switch 1 is
irregular during depressing accelerator pedal. (Other than during shift change)
Possible CauseINFOID:0000000003532417
• ATF pressure switch 1
• Harness or connectors
(The switch circuit is open or shorted.)
DTC Confirmation ProcedureINFOID:0000000003532418
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 POS: 1.5/8 - 2.0/8
Selector lever: “D” position
Gear position: 3rd ⇒ 4th Gear (FR/B 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 (P1841) is detected, go to AT-150, "
Diagnosis Procedure".
If DTC (P1757) is detected, go to AT-134, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000003532419
1.CHECK INPUT SIGNAL
With CONSULT-II
Item name Condition Display value
ATF PRES SW 1Front brake engaged. Refer to AT- 2 0
.ON
Front brake disengaged. Refer to AT- 2 0
.OFF
BCIA0031E

DTC P1841 ATF PRESSURE SWITCH 1
AT-151
< SERVICE INFORMATION >
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1. Start engine.
2. Select “ECU INPUT SIGNALS” or “MAIN SIGNALS” in “DATA
MONITOR” mode for “A/T” with CONSULT-II.
3. Drive vehicle in the “D” position (3rd ⇒ 4th gear), and confirm
the ON/OFF actuation of the “ATF PRES SW 1”.
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 AT-158
.
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 AT-210, "Control Valve with TCM and A/T Fluid Tem-
perature Sensor 2".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to AT-150, "
DTC Confirmation Procedure".
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 1Front brake engaged. Refer to AT- 2 0
.ON
Front brake disengaged. Refer to AT- 2 0
.OFF
PCIA0067E

AT-162
< SERVICE INFORMATION >
BRAKE SIGNAL CIRCUIT
BRAKE SIGNAL CIRCUIT
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000003532442
Diagnosis ProcedureINFOID:0000000003532443
1.CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT-83, "
CONSULT-II Function (A/T)".
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 9 1.
NO >> GO TO 2.
2.CHECK STOP LAMP SWITCH CIRCUIT
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. 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 3 and 4.
Check stop lamp switch after adjusting brake pedal — refer to
BR-5
.
OK or NG
OK >> Check stop lamp switch circuit.
NG >> Repair or replace stop lamp switch.
Item name Condition Display value
BRAKE SWDepressed brake pedal. ON
Released brake pedal. OFF
PCIA0070E
Condition Continuity
When brake pedal is depressed Yes
When brake pedal is released No
WCIA0559E

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-171
< SERVICE INFORMATION >
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DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT-83, "
CONSULT-II Function (A/T)".
Do the self-diagnostic results indicate A/T fluid temperature sensor, engine speed signal, accelerator pedal
position sensor, ATF pressure switch 1, front brake solenoid valve, CAN communication line?
YES >> Check the malfunctioning system. Refer to AT- 11 9, AT-109, AT- 11 7' AT-150' AT-134' AT- 9 1.
NO >> GO TO 2.
2.ENGINE IDLE SPEED
Check the engine idle speed. Refer to EC-75, "
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 AT-208, "
Checking of A/T Position".
OK or NG
OK >> GO TO 4.
NG >> Adjust control cable. Refer to AT-208, "
Adjustment of A/
T Position".
4.CHECK A/T FLUID LEVEL
Check the A/T fluid level. Refer to AT-13, "
Checking Automatic
Transmission Fluid (ATF)".
OK or NG
OK >> GO TO 5.
NG >> Refill ATF.
5.CHECK LINE PRESSURE
Check line pressure at idle with selector lever in “D” position. Refer
to AT-51, "
Inspections Before Trouble Diagnosis".
OK or NG
OK >> GO TO 8.
NG - 1 >> Line pressure high: GO TO 6.
NG - 2 >> Line pressure low: GO TO 7.
6.DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT-210, "
Control Valve with TCM and A/T Fluid Temperature Sen-
sor 2".
2. Disassemble A/T. Refer to AT-240, "
Disassembly".
3. Check the following items:
LCIA0345E
SAT638A
SAT494G

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-173
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1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT-83, "
CONSULT-II Function (A/T)".
Do the self-diagnostic results indicate accelerator pedal position sensor, ATF pressure switch 6, high and low
reverse clutch solenoid valve, CAN communication line, PNP switch?
YES >> Check the malfunctioning system. Refer to AT- 11 7' AT-156, AT-142, AT- 9 1' AT- 9 9.
NO >> GO TO 2.
2.CHECK CONTROL CABLE
Check the control cable.
• Refer to AT-208, "
Checking of A/T Position".
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to AT-208, "
Adjustment of A/
T Position".
3.CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT-13, "
Checking Automatic Trans-
mission Fluid (ATF)".
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4.CHECK STALL TEST
Check stall revolution with selector lever in “1” and “R” positions.
Refer to AT-51, "
Inspections Before Trouble Diagnosis".
OK or NG
OK >> GO TO 6.
OK in “1” position, NG in “R” position>>GO TO 5.
NG in both “1” and “R” positions>>GO TO 8.
5.DETECT MALFUNCTIONING ITEM
1. Disassemble A/T. Refer to AT-240, "
Disassembly".
2. Check the following items:
- Reverse brake. Refer to AT-240, "
Disassembly".
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
6.CHECK LINE PRESSURE
LCIA0345E
SAT638A
SAT493G