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-II Reference Value In Data Monitor Mode:
ECM Terminals And Reference Value:
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:
Always perform test at 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 (TCS switch "OFF") and let it idle for at least 90 seconds.
5. Select "PURG CN/V & S/V P1493" 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 (POS): 900 - 6,300 rpm
Vehicle speed: 36 - 120 km/h (22 - 75 MPH)
B/FUEL SCHDL: 2 - 4.8 msec
Selector lever: Suitable position
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 "TROUBLE DIAGNOSIS FOR DTC P1493".
9. Select "PURG VOL CN P1444" of "EVAPORATIVE SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
10. Touch "START".
If "COMPLETED" is displayed on CONSULT-II screen, go to step 12.
11. 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 20 seconds.)
CMPS-RPM (POS): 900 - 6,300 rpm
Vehicle speed: 36 - 120 km/h (22 - 75 MPH)
B/FUEL SCHDL: 2 - 4.8 msec
Selector lever: Suitable position
If "TESTING" is not displayed after 5 minutes, retry from step 3.
12. Make sure that "OK" is displayed after touching "SELF DIAG RESULTS". If "NG" is displayed, refer to "TROUBLE DIAGNOSIS FOR DTC P1444".
13. Select "VC CUT/V BP/V P1491" of "EVAPORATIVE SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
14. Touch "START".
15. 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 (POS): 900 - 6,300 rpm
Vehicle speed: 36 - 120 km/h (22 - 75 MPH)
B/FUEL SCHDL: 0.5 - 4.5 msec
Selector lever: Suitable position
If "TESTING" is not displayed after 5 minutes, retry from step 3.
16. Make sure that "OK" is displayed after touching "SELF DIAG RESULTS". If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".
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".
DIAGNOSTIC PROCEDURE
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).
EVAP control system pressure sensor
1. Remove EVAP control system pressure sensor with its harness connector connected.
2. Remove hose from EVAP control system pressure sensor.
3. Turn ignition switch "ON".
4. Use pump to apply vacuum and pressure to EVAP control system pressure sensor as shown in figure.
5. Check output voltage between ECM terminal (92) and ground.
CAUTION:
- Always calibrate the vacuum pump gauge when using it.
- Do not apply below -20 kPa (-150 mmHg, -5.91 inHg) or over 20 kPa (150 mmHg, 5.91 inHg) of pressure.
6. If NG, replace EVAP control system pressure sensor.
- Never apply force to the air hole protector of the sensor, if equipped.
- Discard any EVAP control system pressure sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
EVAP canister vent control valve
Check air passage continuity.
With Consult
Perform "VENT CONTROL/V" in "ACTIVE TEST" mode with CONSULT-II.
Without Consult
If NG or operation takes more than 1 second, clean valve using air blower or replace as necessary.
If the portion (B) is rusted, replace EVAP canister vent control valve.
Make sure new O-ring is installed properly.