P0448

DTC P0448 EVAP. EMISSION SYSTEM-VENT CONTROL CIRCUIT SHORTED






GENERAL DESCRIPTION
The evaporative emissions 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 Canister Close Valve (CCV) closes off the air inlet into the canister for leak detection of the evaporative emission system. The CCV also prevents fuel vapors from escaping from the canister. When the engine purges the HC vapors from the canister, the clean air comes into the canister through the canister air-filter and the CCV.

DTC DESCRIPTION
If the level status is high and the surge voltage of CCV is not detected, the PCM determines that a fault exists and a DTC is stored.

Schematic Diagram:

ACTUATOR TEST MODE
1. Connect scantool to Data Link Connector(DLC).
2. Ignition "ON" & Engine "OFF"
3. Select "Actuator Test Mode" on scantool.




4. Using the scantool, operate CCV by force.
5. Does the CCV operate well?

YES: Fault is intermittent caused by poor contact in the sensor" s and/or PCM' s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

NO: Go to "W/Harness Inspection" procedure.

TERMINAL&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.
3. Has a problem been found?

YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.

NO: Go to " Control Circuit Inspection " procedure.

CONTROL CIRCUIT INSPECTION
1. Check for short to battery in harness
1. Ignition "OFF"
2. Disconnect CCV connector.




3. Measure resistance between terminals "1" and "2" of CCV harness connector.

Specification : Infinite

4. Is the measured resistance within specifications?

YES: Go to " Component Inspection " procedure.

NO:
- Check for short to battery in harness between CCV connector and PCM connector.
- Repair or replace as necessary and then, go to " Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION
1. Check CCV
1. Ignition "OFF"
2. Measure resistance between terminals "1" and "2" of the CCV connector.

Specification: Approx. 20 - 32 Ohm (20 °C(68" °F))




3. Monitor the CCV signal waveform and verify that the ground voltage is less than approx. 0.3 V (1) and the surge voltage (2) is between 40 V and 60 V.
4. Is the CCV normal?

YES: Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.

NO: Substitute with a known - good CCV and check for proper operation. If the problem is corrected, replace CCV and go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness test have been verified as " Complete "
5. Are any DTCs present ?

YES: Go to the applicable troubleshooting procedure.

NO: System is performing to specification at this time.