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:
EVAPORATIVE EMISSION SYSTEM DIAGRAM
CONSULT-II 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 (43) (ECM ground).
ON BOARD DIAGNOSIS LOGIC:
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a safe speed.
NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
TESTING CONDITION:
- For best results, perform test at a temperature of 0°C (32°F) or more.
- 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.
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 1 minute.
5. Select "VC CUT/V BP/V P1491" of "EVAPORATIVE 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.) CMPS-RPM (REF): 1,000 - 3,000 rpm Selector lever: Suitable position
Vehicle speed: 36 - 120 kph (22 - 75 MPH)
B/FUEL SCHDL: 0.5 - 3.1 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" below.
OR
OVERALL FUNCTION CHECK
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" below.
Diagnostic Procedure:
DIAGNOSTIC PROCEDURES
COMPONENT INSPECTION
Vacuum cut valve bypass valve
Check air passage continuity.
With Consult
Perform "VC/V BYPASS/V" in "ACTIVE TEST" mode.
OR
Without Consult
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).