2005 INFINITI QX4 sensor

AT-158
DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
Revision: October 20052005 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 ValueECS0 0CJ 0
On Board Diagnosis LogicECS0 0CJ 1

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 CauseECS0 0CJ 2

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

Low coast brake solenoid valve

ATF pressure switch 2
DTC Confirmation ProcedureECS0 0CJ 3
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-159, "
Diagnostic Pro-
cedure" .
If DTC (P1772) is detected, go to AT-157, "
Diagnostic Proce-
dure" .
WITH GST
Follow the procedure “With CONSULT-II”.
Item name Condition Display value
ON OFF SOLLow coast brake engaged. Refer to AT- 1 9
.ON
Low coast brake disengaged. Refer to AT- 1 9
.OFF
ATF PRES SW 2Low coast brake engaged. Refer to AT- 1 9
.ON
Low coast brake disengaged. Refer to AT- 1 9
.OFF
BCIA0030E

DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION
AT-159
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Revision: October 20052005 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-168, "
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 1 , "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 8 , "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- 1 9
.ON
Low coast brake disengaged. Refer to AT- 1 9
.OFF
ATF PRES
SW 2Low coast brake engaged. Refer to AT- 1 9
.ON
Low coast brake disengaged. Refer to AT- 1 9
.OFF
SCIA4794E

DTC P1841 ATF PRESSURE SWITCH 1
AT-161
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Revision: October 20052005 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-168, "
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 1 , "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 0 , "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- 1 9
.ON
Front brake disengaged. Refer to AT - 1 9
.OFF
PCIA0067E

DTC P1843 ATF PRESSURE SWITCH 3
AT-163
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Revision: October 20052005 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-168, "
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 1 , "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 2 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 3Input clutch engaged. Refer to AT-1 9
.ON
Input clutch disengaged. Refer to AT-1 9
.OFF
PCIA0067E

DTC P1845 ATF PRESSURE SWITCH 5
AT-165
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Revision: October 20052005 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-168, "
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 1 , "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 4 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 5Direct clutch egaged. Refer to AT- 1 9
.ON
Direct clutch disegaged. Refer to AT- 1 9
.OFF
PCIA0067E

DTC P1846 ATF PRESSURE SWITCH 6
AT-167
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Revision: October 20052005 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-168, "
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 1 , "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 6 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 2.
Item name Condition Display value
ATF PRES
SW 6High and low reverse clutch engaged.
Refer to AT-1 9
.ON
High and low reverse clutch disengaged.
Refer to AT-1 9
.OFFPCIA0067E

MAIN POWER SUPPLY AND GROUND CIRCUIT
AT-171
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Revision: October 20052005 QX56
7. CHECK TERMINAL CORD ASSEMBLY
1. Remove control valve with TCM. Refer to AT-231, "
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 1 , "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 ConnectorTerminal
(Wire color)Continuity
A/T assembly harness con-
nectorF9 1 (W)
Ye s
TCM connector F502 9 (W)
A/T assembly harness con-
nectorF9 2 (GR)
Ye s
TCM connector F502 10 (GR)
A/T assembly harness con-
nectorF9 6 (R)
Ye s
TCM connector F502 4 (R)
SCIA5464E
Item ConnectorTerminal
(Wire color)Continuity
A/T assembly harness con-
nectorF9 5 (B)
Ye s
TCM connector F504 21 (B)
A/T assembly harness con-
nectorF9 10 (Y)
Ye s
TCM connector F504 22 (Y)
SCIA5465E

AT-182
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: October 20052005 QX56
3. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-231, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT - 1 3 , "
Checking A/T Fluid" .
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-60,
"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 5 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate PNP switch?
YES >> Check the malfunctioning system. Refer to AT-104, "DTC P0705 PARK/NEUTRAL POSITION
SWITCH" .
NO >> GO TO 2.
2. CHECK CONTROL CABLE
Check the control cable.

Refer to AT-228, "Checking of A/T Position" .
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to AT-228, "
Adjustment of A/
T Position" .
SCIA5199E
LCIA0345E