DTC 0801

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




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

Perform "PROCEDURE FOR MALFUNCTION A" first. If DTC cannot be confirmed, perform "OVERALL FUNCTION CHECK", "PROCEDURE FOR MALFUNCTION B".

PROCEDURE FOR MALFUNCTION A
WITH CONSULT
(1) Turn ignition switch "ON".
(2) Select "DATA MONITOR" mode with CONSULT
(3) Start engine and wait at least 5 seconds.

OR

WITH GST
(1) Start engine and wait at least 5 seconds.
(2) Select "MODE 3" with GST

OR

WITH NO TOOLS
(1) Start engine and wait at least 5 seconds.
(2) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(3) Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.

OVERALL FUNCTION CHECK
PROCEDURE FOR MALFUNCTION B
(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 terminals.
(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).

EC-BYPS/V-01 Vacuum Cut Valve Bypass Valve (DTC: 0801):

WIRING DIAGRAM




DIAGNOSTIC PROCEDURE A




DIAGNOSTIC PROCEDURE B

COMPONENT INSPECTION
Vacuum Cut Valve Bypass Valve




Check air passage continuity.




If NG, 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).