Nissan Qashqai J11. Manual - part 506

EC9-180

< DTC/CIRCUIT DIAGNOSIS >

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B1903 DC/DC CONVERTER

B1903 DC/DC CONVERTER

DTC Logic

INFOID:0000000010309079

DTC DETECTION LOGIC

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 

EC9-39, "STOP/START SYSTEM : System Description (M/T models)"

(M/T models), 

EC9-47, "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 

EC9-180, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010309080

1.

CHECK FUSE

Check that the following fuse is not fusing.

Refer to 

PG-11, "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 2 CIRCUIT

1.

Disconnect the accessory relay.

DTC

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

Possible cause

B1903

—
(—)

DC/DC converter detects power supply 
output 2 is 5.0 V or less when restart 
the engine.

• Harness and connectors

(DC/DC converter power supply output 2 
circuit is open or shorted.)

• DC/DC converter
• Components power-supplied from DC/DC 

output 2

Fuse No.

Capacity

#76

10 A

#77

10 A

B1903 DC/DC CONVERTER

EC9-181

< DTC/CIRCUIT DIAGNOSIS >

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2.

Disconnect DC/DC converter harness connector.

3.

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

Refer to 

PG-11, "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 ACCESSORY 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-41, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace DC/DC converter. Refer to 

EC9-408, "Removal and Installation"

.

NO

>> Repair or replace error-detected parts.

+

−

Continuity

DC/DC converter

Accessory relay

Connector

Terminal

M23

6

Switching circuit (+)

Existed

EC9-182

< DTC/CIRCUIT DIAGNOSIS >

[R9M]

B1904 DC/DC CONVERTER

B1904 DC/DC CONVERTER

DTC Logic

INFOID:0000000010309081

DTC DETECTION LOGIC

NOTE:
If DTC B1904 is displayed with DTC B1900 or B1901, perform the trouble diagnosis for DTC B1900 or B1901.
Refer to 

EC9-174, "DTC Logic"

 or 

EC9-176, "DTC Logic"

.

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 

EC9-39, "STOP/START SYSTEM : System Description (M/T models)"

(M/T models), 

EC9-47, "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 

EC9-182, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010309082

1.

INSPECTION START

1.

Turn ignition switch ON.

2.

Erase DTC.

3.

Perform DTC Confirmation Procedure. Refer to 

EC9-182, "DTC Logic"

.

4.

Check DTC.

Is the DTC B1904 displayed again?

YES

>> Replace DC/DC converter. Refer to 

EC9-408, "Removal and Installation"

.

NO

>> INSPECTION END

DTC

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

Possible cause

B1904

—
(—)

DC/DC converter function is malfunc-
tioning.

DC/DC converter

P0001 FUEL PUMP

EC9-183

< DTC/CIRCUIT DIAGNOSIS >

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P0001 FUEL PUMP

DTC Logic

INFOID:0000000010309083

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 1 minute before conducting the next test.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch ON and wait at least 1 second.

2.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC9-183, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000010309084

1.

CHECK FUEL FLOW ACTUATOR POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect fuel flow actuator harness connector.

3.

Turn ignition switch ON.

4.

Check the voltage between fuel flow actuator harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Perform the trouble diagnosis for power supply circuit.

2.

CHECK FUEL FLOW ACTUATOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between fuel flow actuator harness connector and ECM harness connector.

DTC No.

CONSULT screen terms

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0001

FUEL FLOW REGULATOR CIR-
CUIT
(Fuel volume regulator control 
circuit/open)
• 1.DEF: INLET FLAP 

BLOCKED CLOSED

• 2.DEF: INLET FLAP 

BLOCKED OPEN

• 3.DEF: OPERATION TEM-

PERATURE TOO HIGH

• ECM detects a short circuit to ground.
• ECM detects a short circuit to battery.
• ECM detects a open circuit.
• ECM detects an over temperature.

• Harness or connectors

(Fuel flow actuator circuit is 
open or shorted.)

• Fuel flow actuator

+

-

Voltage

Fuel flow actuator

Connector

Terminal

F123

1

Ground

Battery voltage