sensor INFINITI QX56 2006 Factory Service Manual

DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTIONAT-157
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Revision: November 2009 2006 QX56
DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTIONPFP:31940
DescriptionECS00CIZ

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 mal-
function such as control valve sticking, improper solenoid valve operation.
CONSULT-II Reference ValueECS00CJ0
On Board Diagnosis LogicECS00CJ1

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 CauseECS00CJ2

Harness or connectors
(The solenoid and switch circuits are open or shorted.)

Low coast brake solenoid valve

ATF pressure switch 2
DTC Confirmation ProcedureECS00CJ3
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- 1 5 8 , "
Diagnostic Pro-
cedure" .
If DTC (P1772) is detected, go to AT- 1 5 6 , "
Diagnostic Proce-
dure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value
ON OFF SOL Low coast brake engaged. Refer to
AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
ATF PRES SW 2 Low coast brake engaged. Refer to
AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
BCIA0030E

AT-158
DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CJ4
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- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 5 7 , "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
AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
ATF PRES
SW 2 Low coast brake engaged. Refer to
AT- 2 0
.ON
Low coast brake disengaged. Refer to AT- 2 0
.OFF
SCIA4794E

AT-160
DTC P1841 ATF PRESSURE SWITCH 1
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CJA
1. CHECK INPUT SIGNAL
With CONSULT-II
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- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 5 9 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 1 Front brake engaged. Refer to
AT- 2 0
.ON
Front brake disengaged. Refer to AT- 2 0
.OFF
PCIA0067E

AT-162
DTC P1843 ATF PRESSURE SWITCH 3
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CJG
1. CHECK INPUT SIGNAL
With CONSULT-II
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 3”.
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- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 6 1 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 3 Input clutch engaged. Refer to
AT- 2 0
.ON
Input clutch disengaged. Refer to AT- 2 0
.OFF
PCIA0067E

AT-164
DTC P1845 ATF PRESSURE SWITCH 5
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CJM
1. CHECK INPUT SIGNAL
With CONSULT-II
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 (1st
2nd gear), and confirm
the ON/OFF actuation of the “ATF PRES SW 5”.
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- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 6 3 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 5 Direct clutch egaged. Refer to
AT- 2 0
.ON
Direct clutch disegaged. Refer to AT- 2 0
.OFF
PCIA0067E

AT-166
DTC P1846 ATF PRESSURE SWITCH 6
Revision: November 20092006 QX56
Diagnostic ProcedureECS00CJS
1. CHECK INPUT SIGNAL
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 “D ” position (2nd
3rd gear), and confirm
the ON/OFF actuation of the “ATF PRES SW 6”.
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- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
4. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 6 5 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 6 High and low reverse clutch engaged.
Refer to
AT- 2 0
. ON
High and low reverse clutch disengaged.
Refer to AT- 2 0
. OFFPCIA0067E

AT-170
MAIN POWER SUPPLY AND GROUND CIRCUIT
Revision: November 20092006 QX56
7. CHECK TERMINAL CORD ASSEMBLY
1. Remove control valve with TCM. Refer to AT- 2 3 0 , "
Control Valve With TCM and A/T Fluid Temperature
Sensor 2" .
2. Disconnect A/T assembly harness connector and TCM connector.
3. Check continuity between A/T assembly harness connector ter- minals and TCM connector terminals.
4. Check continuity between A/T assembly harness connector ter- minals and TCM connector terminals.
5. If OK, check harness for short to ground and short to power.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Replace open circuit or short to ground and short to power in harness or connectors.
Item Connector Terminal Continuity
A/T assembly harness con-
nector F9
1
Ye s
TCM connector F5029
A/T assembly harness con-
nector F9
2
Ye s
TCM connector F50210
A/T assembly harness con-
nector F9
6
Ye s
TCM connector F5024
SCIA5464E
Item Connector Terminal Continuity
A/T assembly harness con-
nector F9
5
Ye s
TCM connector F50421
A/T assembly harness con-
nector F9
10
Ye s
TCM connector F50422
SCIA5465E

TROUBLE DIAGNOSIS FOR SYMPTOMSAT-181
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Revision: November 2009 2006 QX56
3. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT- 2 3 0 , "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 1 2 , "
Checking Automatic
Transmission Fluid (ATF)" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 4.
4. DETECT MALFUNCTIONING ITEM

Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT- 6 1 ,
"Symptom Chart" (Symptom No.58).
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
In “N” Position, Vehicle MovesECS00CK6
SYMPTOM:
Vehicle moves forward or backward when selecting “N” position.
DIAGNOSTIC PROCEDURE
1. CHECK PNP SWITCH CIRCUIT
Perform self-diagnosis. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate PNP switch?
YES >> Check the malfunctioning system. Refer to AT- 1 0 5 , "DTC P0705 PARK/NEUTRAL POSITION
SWITCH" .
NO >> GO TO 2.
2. CHECK CONTROL CABLE
Check the control cable.

Refer to AT- 2 2 7 , "Checking of A/T Position" .
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to AT- 2 2 7 , "
Adjustment of A/
T Position" .
SCIA5199E
LCIA0345E

AT-182
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: November 20092006 QX56
3. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT- 1 2 , "
Checking Automatic Trans-
mission Fluid (ATF)" .
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT- 2 3 0 , "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 1 2 , "
Checking Automatic
Transmission Fluid (ATF)" .
OK or NG
OK >> GO TO 5.
NG >> Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT- 6 1 , "
Symp-
tom Chart" (Symptom No.60).
5. CHECK SYMPTOM
Check again. Refer to AT- 5 5 , "
Check at Idle" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 6.
6. PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to AT- 8 3 , "
TCM Input/Output Signal Reference Val-
ues" .
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
Large Shock (“N” to “D” Position)ECS00CK7
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 AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
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- 1 2 7 , "DTC P1710 A/T FLUID TEMPERATURE
SENSOR CIRCUIT" , AT- 11 6 , "DTC P0725 ENGINE SPEED SIGNAL" ., AT- 1 2 4 , "DTC P1705
SAT638A
SCIA5199E

TROUBLE DIAGNOSIS FOR SYMPTOMSAT-183
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Revision: November 2009 2006 QX56
THROTTLE POSITION SENSOR" , AT- 1 5 9 , "DTC P1841 ATF PRESSURE SWITCH 1" , AT- 1 4 3 ,
"DTC P1757 FRONT BRAKE SOLENOID VALVE" , AT- 9 6 , "DTC U1000 CAN COMMUNICATION
LINE" .
NO >> GO TO 2.
2. ENGINE IDLE SPEED
Check the engine idle speed. Refer to EC-76, "
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- 2 2 7 , "Checking of A/T Position" .
OK or NG
OK >> GO TO 4.
NG >> Adjust control cable. Refer to AT- 2 2 7 , "
Adjustment of A/
T Position" .
4. CHECK A/T FLUID LEVEL
Check the A/T fluid level. Refer to AT- 1 2 , "
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- 5 2 , "
LINE PRESSURE TEST" .
OK or NG
OK >> GO TO 8.
NG - 1 >> Line pressure high: GO TO 6.
NG - 2 >> Line pressure low: GO TO 7.
LCIA0345E
SAT638A
SAT494G