Infiniti Q45. Manual - part 61

 

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Infiniti Q45. Manual - part 61

 

 

DTC P1772 LOW COAST BRAKE SOLENOID VALVE

AT-157

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DTC P1772 LOW COAST BRAKE SOLENOID VALVE

PFP:31940

Description

NCS000YW

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.

CONSULT-II Reference Value

NCS000YX

On Board Diagnosis Logic

NCS000YY

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P1772 LC/B SOLENOID/CIRC” with CONSULT-II or 7th judgement flicker with-
out CONSULT-II is detected when TCM detects an improper voltage drop when it tries to operate the sole-
noid valve.

Possible Cause

NCS000YZ

Harness or connectors
(Solenoid circuit is open or shorted.)

Low coast brake solenoid valve 

DTC Confirmation Procedure

NCS000Z0

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.

Turn ignition switch ON. (Do not start engine.)

2.

Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II and check monitor “MANU MODE
SW” and “GEAR”.

3.

Touch “START”.

4.

Start engine.

5.

Drive vehicle and maintain the following conditions for at least 5
consecutive seconds.
MANU MODE SW: ON 
GEAR: “1” or “2” (LC/B ON/OFF)

6.

If DTC is detected, go to 

AT-158, "Diagnostic Procedure"

 .

 WITH GST

Follow the procedure “WITH CONSULT-II”.

Item name

Condition 

Display value 

ON OFF SOL

Low coast brake engaged. Refer to 

AT-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

BCIA0031E

AT-158

DTC P1772 LOW COAST BRAKE SOLENOID VALVE

Diagnostic Procedure

NCS000Z1

1. 

CHECK INPUT SIGNAL

 With CONSULT-II

1.

Turn ignition switch ON. (Do not start engine.)

2.

Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II.

3.

Start 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-173, "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.

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-225, "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-157, "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-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

SCIA4794E

DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION

AT-159

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DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION

PFP:31940

Description

NCS000Z2

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 Value

NCS000Z3

On Board Diagnosis Logic

NCS000Z4

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P1774 LC/B SOLENOID FNCT” with CONSULT-II or 7th judgement flicker with-
out 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 Cause

NCS000Z5

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

Low coast brake solenoid valve 

ATF pressure switch 2

DTC Confirmation Procedure

NCS000Z6

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.
MANU MODE SW: ON 
GEAR: “1” or “2” (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, go to 

AT-160, "Diagnostic Proce-

dure"

 .

If DTC (P1772) is detected, go to 

AT-158, "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-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

ATF PRES SW 2

Low coast brake engaged. Refer to 

AT-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

BCIA0031E

AT-160

DTC P1774 LOW COAST BRAKE SOLENOID VALVE FUNCTION

Diagnostic Procedure

NCS000Z7

1. 

CHECK INPUT SIGNALS

 With CONSULT-II

1.

Start engine.

2.

Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “A/T” with CONSULT-II.

3.

Drive vehicle in the manual mode (1st or 2nd 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-173, "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.

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-225, "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-159, "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-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

ATF PRES SW 2

Low coast brake engaged. Refer to 

AT-19

 

.

ON

Low coast brake disengaged. Refer to 

AT-19

 

.

OFF

SCIA4794E

 

 

 

 

 

 

 

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