P1491

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 Reference Value in Data Monitor Mode
Specification data are reference values.




ECM Terminals and Reference Value
Specification data are reference values and are measured between each terminal and 32 (ECM ground).

On Board Diagnosis Logic:

DTC Confirmation Procedure

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 0 to 30 °C (32 to 86 °F).

With CONSULT
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 70 seconds.
5. Select "VC CUT/V BP/V P1491" of "EVAPORATIVE SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT.
6. Touch "START".










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

CMPS-RPM (POS): 500 - 3,000 rpm
Selector lever: Suitable position
Vehicle speed: 36 - 120 KPH (22 - 75 MPH)
B/FUEL SCHDL: Less than 5 msec

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 "Diagnostic Procedure".

Overall Function Check
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.




Without CONSULT
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 "Diagnostic Procedure".

EC-BYPS/V-01:

EC-BYPS/V-01 Connector View:

Wiring Diagram

M1, E1, M2, B1:

M10, E3, M91:

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

Step 6:

Step 7:

Step 8:

Step 9:

Step 10:

Step 11:

Step 12:

Diagnostic Procedure

Component Inspection

VACUUM CUT VALVE BYPASS VALVE
Check air passage continuity.




With CONSULT
Perform "VC/V BYPASS/V" in "ACTIVE TEST" mode.

Condition VC/V BYPASS/V: Air passage continuity between A and B
ON: Yes
OFF: No




Without CONSULT
Air passage continuity

Condition: Air passage continuity between A and B
12 V direct current supply between terminals: Yes
No supply: No

If NG or operation takes more than 1 second, replace vacuum cut valve bypass valve.




VACUUM CUT VALVE
Check vacuum cut valve as follows:
1. Plug port C and D with fingers.
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. Open port C and D.
6. Blow air in port A check that air flows freely out of port C.
7. Blow air in port B check that air flows freely out of port D.