If there is a malfunction detected in the evaporative emission (EVAP) VSV, the canister closed valve (CCV) and the bypass valve; the ECM will illuminate the MIL and set a DTC.
This portion of the EVAP diagnosis checks the following EVAP system functions
- CCV stuck closed. The ECM checks for a CCV "stuck closed" malfunction by commanding the CCV to open after an EVAP leak test. If the fuel tank pressure does not rise (lose vacuum), the ECM determines that the CCV is stuck closed. The ECM will turn on the MIL and a DTC is set.
- Pressure switching valve stuck closed. The ECM checks for a pressure switching valve "stuck closed" malfunction by commanding the pressure switching valve to close after an EVAP leak test. If the fuel tank pressure does not change, the ECM determines that the pressure switching valve is malfunctioning. The ECM will turn on the MIL and a DTC is set.
- EVAP VSV (Purge line to intake manifold) stuck closed. The ECM checks for a stuck closed malfunction in the EVAP VSV by commanding it to open with the CCV closed. If a high negative pressure does not develop in the fuel tank, the ECM determines that the EVAP VSV remains closed. The ECM turns on the MIL and a DTC is set.
Scheme 729
HINT
Typical DTC output of each trouble part.
