Nissan Frontier D22. Manual - part 351

DTC P1491 VACUUM CUT VALVE BYPASS VALVE

EC-507

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DTC P1491 VACUUM CUT VALVE BYPASS VALVE

PFP:17372

Description

UBS00DC7

COMPONENT DESCRIPTION

The vacuum cut valve and vacuum cut valve bypass valve are
installed in parallel on the EVAP purge line between the fuel tank and
the EVAP canister.
The vacuum cut valve prevents the intake manifold vacuum from
being applied to the fuel tank.
The vacuum cut valve bypass valve is a solenoid type valve and
generally remains closed. It opens only for on board diagnosis.
The vacuum cut valve bypass valve responds to signals from the
ECM. When the ECM sends an ON (ground) signal, the valve is
opened. The vacuum cut valve is then bypassed to apply intake
manifold vacuum to the fuel tank.

EVAPORATIVE EMISSION SYSTEM DIAGRAM

CONSULT-II Reference Value in Data Monitor Mode

UBS00DC8

Specification data are reference values.

SEF186S

PBIB1402E

MONITOR ITEM

CONDITION

SPECIFICATION

VC/V BYPASS/V

●

Ignition switch: ON

OFF

EC-508

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DTC P1491 VACUUM CUT VALVE BYPASS VALVE

On Board Diagnosis Logic

UBS00DC9

DTC Confirmation Procedure

UBS00DCA

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously conducted, always turn ignition switch OFF and wait at
least 5 seconds before conducting the next test.
TESTING CONDITION:

●

Always perform test at a temperature of 5 to 30

°C (41 to 86°F).

●

This test may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a
road test is expected to be easier, it is unnecessary to lift the vehicle.

●

Before performing the following procedure, confirm that battery voltage is more than 11V at idle.

 WITH CONSULT-II

1.

Turn ignition switch ON.

2.

Start engine and warm it up to normal operating temperature.

3.

Turn ignition switch OFF and wait at least 5 seconds.

4.

Start engine and let it idle for at least 60 seconds.

5.

Select “VC CUT/V BP/V P1491” of “EVAP SYSTEM” in “DTC WORK SUPPORT” mode with CONSULT-II.

6.

Touch “START”.

7.

When the following conditions are met, “TESTING” will be displayed on the CONSULT-II screen. Maintain
the conditions continuously until “TESTING” changes to “COMPLETED”. (It will take at least 30 seconds.)

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1491

Vacuum cut valve 
bypass valve

Vacuum cut valve bypass valve does 
not operate properly.

●

Vacuum cut valve bypass valve

●

Vacuum cut valve

●

Bypass hoses for clogging

●

EVAP control system pressure sensor and circuit

●

EVAP canister vent control valve

●

Hose between fuel tank and vacuum cut valve 
clogged

●

Hose between vacuum cut valve and EVAP canister 
clogged

●

EVAP canister

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EVAP purge port of fuel tank for clogging

●

Refueling control valve

●

Refueling EVAP vapor cut valve

ENG SPEED

1,000 rpm - 3,750 rpm 

Selector lever

Suitable position

Vehicle speed

36 - 120 km/h (22 - 75 MPH)

B/FUEL SCHDL

Less than 10 msec

DTC P1491 VACUUM CUT VALVE BYPASS VALVE

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If “TESTING” is not displayed after 5 minutes, retry from step 3.

8.

Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”. If “NG” is displayed, refer to 

EC-

511, "Diagnostic Procedure"

Overall Function Check

UBS00DCB

Use this procedure to check the overall function of vacuum cut valve bypass valve. During this check, the 1st
trip DTC might not be confirmed.

 WITH GST

1.

Remove vacuum cut valve and vacuum cut valve bypass valve as an assembly.

2.

Apply vacuum to port A  and check that there is no suction from port B .

3.

Apply vacuum to port B  and check that there is suction from port A .

4.

Blow air in port B  and check that there is a resistance to flow out of port A .

5.

Supply battery voltage to the terminal.

6.

Blow air in port A  and check that air flows freely out of port B .

7.

Blow air in port B  and check that air flows freely out of port A .

8.

If NG, go to 

EC-511, "Diagnostic Procedure"

 .

PBIB0841E

SEF530Q

EC-510

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DTC P1491 VACUUM CUT VALVE BYPASS VALVE

Wiring Diagram

UBS00DCC

BBWA1067E