Toyota Tacoma manuals

Toyota Corolla Repair Manual: Circuit description

The vapor pressure sensor, vsv for canister closed valve (ccv), vsv for pressure switching valve are used to detect abnormalities in the evaporative emission control system.

The ecm decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal.

Dtcs p0441 and p0446 are recorded by the ecm when evaporative emissions leak from the components within the dotted line in fig. 1 Below, or when there is malfunction in both vsv for evap and vsv for pressure switching valve, or in the vapor pressure sensor itself.

Hint:

Hint

: typical dtc output of each trouble part.

*1: Ecm may output some other dtcs combination.

*1: Ecm may output some other dtcs combination.

*2: Refer to p0442 and p0456.

Monitor description

P0441

The ecm checks for a stuck closed malfunction in the vsv for evap by commanding it to open with the ccv closed. If a high negative pressure does not develop inthe fuel tank, the ecm determines that the vsv for evap remains closed. The ecm turns on the mil and a dtc is set.

The ecm checks for vsv for evap stuck open fault by commanding both valves (vsv for evap and ccv) to close at a time when the fuel tank is at atmospheric pressure. If the fuel tank develops a high negative pressure at this early stage of the test, the ecm determines that the vsv for evap is stuck open.

The ecm will turn on the mil and a dtc is set.

P0446

If there is a malfunction detected in the vsv for evaporative emission (evap), the canister closed valve (ccv) and the vsv for bypass valve; the ecm will illuminate the mil and set a dtc.

This portion of the evap diagnosis checks the following evap system functions:

  1.  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.

  2.  vsv for pressure switching valve stuck closed.

    The ecm checks for a vsv for pressure switching valve stuck closed malfunction by commanding the vsv for pressure switching valve to close after an evap leak test. If the fuel tank pressure does not change, the ecm determines that the vsv for pressure switching valve is malfunctioning. The ecm will turn on the mil and a dtc is set.

  3.  vsv for evap (purge line to intake manifold) stuck closed.

    The ecm checks for a stuck closed malfunction in the vsv for evap by commanding it to open with the ccv closed. If a high negative pressure does not develop inthe fuel tank, the ecm determines that the vsv for evap remains closed. The ecm turns on the mil and a dtc is set.

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

P0441

P0446

P0446

Monitor result (mode 06 data)

Monitor result (mode 06 data)

Refer  for the detailed information on checking monitor status.

Refer  for the detailed information on checking monitor status.

Wiring diagram

Inspection procedure

Evaporative emission control system
Dtc p0441 evaporative emission control system incorrect purge flow Dtc p0446 evaporative emission control system vent control circuit ...

Inspection procedure
Hint: if dtc p0441 (purge flow), p0446 (vsv for ccv or vsv for pressure switching valve), p0451, p0452 or p0453  is output with dtc p0442 or p0456 , first troubleshoot dtc p0441, p0446 ...

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