Nissan X-Trail 32. Manual - part 962

B1901 DC/DC CONVERTER

EC-977

< DTC/CIRCUIT DIAGNOSIS >

[R9M]

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B1901 DC/DC CONVERTER

DTC Description

INFOID:0000000010935638

DTC DETECTION LOGIC

POSSIBLE CAUSE

• Harness and connectors (DC/DC converter power supply input 2 circuit is open or shorted.)
• DC/DC converter

FAIL-SAFE

STOP/START SYSTEM

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If the other DTC Confirmation Procedure is performed right before this procedure, the ignition switch must be
turned OFF and wait for 10 seconds or more to start this procedure.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-1

1.

Turn ignition switch ON and wait at least 3 seconds.

2.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC-978, "Diagnosis Procedure"

.

NO

>> GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE-2

With CONSULT

1.

Start the engine and warm it up to normal operating temperature.

2.

Press start/stop OFF switch and check that the switch indicator is ON.

3.

Select “AUTO STOP START” in “ACTIVE TEST” mode of “ENGINE” using CONSULT.

4.

Touch “START” and operate stop/start system. (engine stop.)

5.

Touch “CANCEL” and restart the engine.

6.

Check DTC.

Without CONSULT

1.

Activate stop/start system. Refer to 

EC-848, "STOP/START SYSTEM : System Description (M/T models)"

(M/T models), 

EC-856, "STOP/START SYSTEM : System Description (CVT models)"

.

CAUTION:

Always drive vehicle at a safe speed.

2.

Restart the engine.

3.

Check DTC.

Is DTC detected?

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

B1901

—
(—)

DC/DC converter detects power supply input 2 is 5.0 V or less and differ-
ence between power supply input 2 and power supply input 1 is 4.0 V or 
more for 3 seconds.

Stop/start system operating condition in fail safe mode

Idling or driving the vehicle

Stop/start system operating

Stop

During cranking

(Restart)

Prohibit the stop/start system operation

Restart the engine

Prohibit the stop/start system operation 
from the next time

EC-978

< DTC/CIRCUIT DIAGNOSIS >

[R9M]

B1901 DC/DC CONVERTER

YES

>> Proceed to 

EC-978, "Diagnosis Procedure"

.

NO-1

>> To check malfunction symptom before repair: Refer to 

GI-44, "Intermittent Incident"

.

NO-2

>> Confirmation after repair: INSPECTION END

Diagnosis Procedure

INFOID:0000000010935639

1.

CHECK FUSE

1.

Turn ignition switch OFF.

2.

Check that the following fuse is not fusing.

Is the fuse fusing?

YES

>> Replace the fuse after repairing the applicable circuit.

NO

>> GO TO 2.

2.

CHECK DC/DC CONVERTER POWER SUPPLY INPUT 2

1.

Disconnect DC/DC converter harness connector.

2.

Check the voltage between DC/DC converter harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> GO TO 3.

3.

CHECK DC/DC CONVERTER POWER SUPPLY INPUT 2 CIRCUIT

1.

Disconnect battery negative terminal.

2.

Check the continuity between DC/DC converter harness connector and fuse.

Is the inspection result normal?

YES

>> Perform the trouble diagnosis for power supply circuit.

NO

>> Repair or replace error-detected parts.

4.

CHECK INTERMITTENT INCIDENT

Perform intermittent incident. Refer to 

GI-44, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace DC/DC converter. Refer to 

EC-1229, "Removal and Installation"

.

NO

>> Repair or replace error-detected parts.

Fuse No.

Capacity

F/L-N

30 A

+

−

Voltage

DC/DC converter

Connector

Terminal

M97

3

Ground

Battery voltage

+

−

Continuity

DC/DC converter

Fuse No.

Connector

Terminal

M97

3

F/L-N

Existed

B1902 DC/DC CONVERTER

EC-979

< DTC/CIRCUIT DIAGNOSIS >

[R9M]

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B1902 DC/DC CONVERTER

DTC Description

INFOID:0000000010935640

DTC DETECTION LOGIC

POSSIBLE CAUSE

• Harness and connectors (DC/DC converter power supply output 1 circuit is open or shorted.)
• DC/DC converter
• Components power-supplied from DC/DC output 1

FAIL-SAFE

STOP/START SYSTEM

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If the other DTC Confirmation Procedure is performed right before this procedure, the ignition switch must be
turned OFF and wait for 10 seconds or more to start this procedure.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT

1.

Start the engine and warm it up to normal operating temperature.

2.

Press start/stop OFF switch and check that the switch indicator is ON.

3.

Select “AUTO STOP START” in “ACTIVE TEST” mode of “ENGINE” using CONSULT.

4.

Touch “START” and operate stop/start system. (Stop the engine.)

5.

Touch “CANCEL” and restart the engine.

6.

Check DTC.

Without CONSULT

1.

Activate stop/start system. Refer to 

EC-848, "STOP/START SYSTEM : System Description (M/T models)"

(M/T models), 

EC-856, "STOP/START SYSTEM : System Description (CVT models)"

 (CVT models).

CAUTION:

Always drive vehicle at a safe speed.

2.

Restart the engine.

3.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC-979, "Diagnosis Procedure"

.

NO-1

>> To check malfunction symptom before repair: Refer to 

GI-44, "Intermittent Incident"

.

NO-2

>> Confirmation after repair: INSPECTION END

Diagnosis Procedure

INFOID:0000000010935641

1.

CHECK FUSE

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

B1902

—
(—)

DC/DC converter detects power supply output 1 is 5.0 V or less when re-
start the engine.

Stop/start system operating condition in fail safe mode

Idling or driving the vehicle

Stop/start system operating

Stop

During cranking

(Restart)

Prohibit the stop/start system operation

Restart the engine

Prohibit the stop/start system operation 
from the next time

EC-980

< DTC/CIRCUIT DIAGNOSIS >

[R9M]

B1902 DC/DC CONVERTER

Check that the following fuse is not fusing.

Refer to 

PG-12, "Wiring Diagram - BATTERY POWER SUPPLY -"

.

Is the fuse fusing?

YES

>> Replace the fuse after repairing the applicable circuit.

NO

>> GO TO 2.

2.

CHECK DC/DC CONVERTER POWER SUPPLY OUTPUT 1 CIRCUIT

1.

Disconnect the ignition relay.

2.

Disconnect DC/DC converter harness connector.

3.

Check the continuity between DC/DC converter harness connector ignition relay harness connector.

Refer to 

PG-12, "Wiring Diagram - BATTERY POWER SUPPLY -"

.

4.

Also check harness for short to ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace error-detected parts.

3.

CHECK IGNITION RELAY ROUTING CIRCUIT

Check ignition relay routing circuit.
Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair or replace error-detected parts.

4.

CHECK INTERMITTENT INCIDENT

Perform intermittent incident. Refer to 

GI-44, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace DC/DC converter. Refer to 

EC-1229, "Removal and Installation"

.

NO

>> Repair or replace error-detected parts.

Fuse No.

Capacity

#54

10 A

#55

10 A

#56

10 A

#57

10 A

+

−

Continuity

DC/DC converter

Ignition relay

Connector

Terminal

M97

4

Switching circuit (+)

Existed