P0444 Evaporative Emission System-Purge Control Valve Circuit Open

COMPONENT LOCATION

GENERAL DESCRIPTION

The evaporative emission control system prevents hydrocarbon (HC) vapors from the fuel tank from escaping into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The ECM controls the Purge Control Solenoid Valve (PCSV) to purge any collected vapors from the canister back to the engine for combustion. This valve is actuated by the purge control signal from the ECM and controls fuel vapor from the canister to the intake manifold.

DTC DESCRIPTION

Checking output signals from PCSV every 10 sec. under detecting condition, if signals indicating open or short to ground in the circuit are detected for more than 5 sec., ECM sets P0444.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Open, short to ground

1.	Poor connection

2.	Open or short to ground in harness

PCSV

ECM

Enable Conditions

Engine running state

11V ≤ Battery voltage ≤ 16V

Above enable conditions are met > 0.5 sec.

Threshold value

Open or short to ground

Diagnosis Time

Continous (More than 5 sec.failure for every 10 sec.test)

MIL On Condition

3 driving cycles

SPECIFICATION

Item	Coil resistance(Ω)
PCSV	22.0 ~ 26.0 [20°C(68°F)]

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal waveform of PCSV under 27% control condition.

Fig.2) Abnormal data of PCSV when PCSV circuit open.

The Purge Control Solenoid Valve(PCSV) is open or closed by ECM and vacuum of intake manifold.

At opening, fuel vapor from canister enters into intake manifold. To prevent vacuum from forming inside canister, ECM controls to open it. This photo shows the signal waveform of PCSV operating normally.

MONITOR GDS DATA

1.	Connect GDS to Data Link Connector(DLC).

IG “ON”.

3.	Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu.

4.	Read “DTC Status” parameter.

Is parameter displayed “Present fault”?

	▶ Go to “Terminal and Connector inspection” procedure.
	▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to “Verification of Vehicle Repair” procedure
	▶ Go to ” Power Circuit Inspection ” procedure.

POWER CIRCUIT INSPECTION

■ Check voltage

1.	IG “OFF” and disconnect PCSV connector.

IG “ON”.

Measure voltage between control terminal of PCSV harness connector and chassis ground.

B+

Is the measured voltage within specification ?

	▶ Go to “Control Circuit Inspection” procedure.
	▶ Repair open or short to ground inharness, and go to “Verification of Vehicle Repair” procedure.

CONTROL CIRCUIT INSPECTION

■ Check short to ground in harness

1.	IG “OFF” and disconnect PCSV connector and ECM connector.

Measure resistance between control terminal of PCSV harness connector and chassis ground.

Infinite

Is the measured voltage within specification ?

	▶ Go to “Check open in harness” as follows.
	▶ Repair short to ground in harness, and go to ” Verification of Vehicle Repair” procedure.

■ Check open in harness

1.	IG “OFF” and disconnect PCSV connector and ECM connector.

Measure resistance between control terminal of PCSV harness connector and PCSV control terminal of ECM harness connector.

Below 1Ω

Is the measured resistance within specification?

	▶ Go to ” Component Inspection” procedure.
	▶ Repair open in harness

COMPONENT INSPECTION

■ Check PCSV

1.	IG “OFF” and disconnect PCSV connector.

Measure resistance between power and control terminals of PCSV connector.(Component side)

22.0 ~ 26.0Ω [20°C(68°F)]

Is the measured siganl waveform normal?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.

There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others.

▶ Substitute with a known – good PCSV and check for proper operation. If the problem is corrected, replace PCSV

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