P0448
DTC P0448 EVAP. EMISSION SYSTEM-VENT CONTROL CIRCUIT SHORTEDComponent Location:
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 Closing 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
Checking output signals from PCSV every 10 sec. under detecting condition, if signals indicating short to battery in the circuit are detected for more than 5 sec., PCM sets P0448. MIL (Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
SPECIFICATION
Item Specification
Coil Resistance (Ohms) 19.8 - 21.852 (20 degrees C)
Schematic Diagram:
MONITOR DTC STATUS
1. Connect scantool to Data Link Connector (DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes (DTCs)" mode, and then Press F4 (DTAL) to check DTC's information from the DTCs menu
4. Read "DTC Status" parameter.
5. Is parameter displayed "Present fault"?
YES - Go to "Actuation Test" procedure.
NO - Fault is intermittent, go to "Verification of vehicle Repair" procedure.
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.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO - Go to "Power Circuit Inspection" procedure.
CONTROL CIRCUIT INSPECTION
1. Check for short to ground in harness.
1. Ignition "OFF"
2. Disconnect CCV connector
3. Measure resistance between terminal "2" of CCV harness connector and chassis ground.
Specification : Infinite
4. Is the measured resistance within specifications?
YES - Go to "Check for open in harness" as below.
NO
- Check short to ground in signal harness.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
2. Check for open in harness.
1. Ignition "OFF"
2. Disconnect CCV and PCM connector
3. Measure resistance between terminal "2" of CCV harness connector and terminal "37" of PCM harness connector.
Specification : Approx. below 1 Ohm
3. Is the measured resistance within specifications?
YES - Go to "Component Inspection" procedure.
NO
- Check open 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 19.8 -21.8 Ohms (20 degrees C (68 degrees F))
3. Monitor the CCV signal waveform and verify that the ground voltage is less than approx. 0.3 V (0)and the surge voltage (a) 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.
NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History (Not Present) fault"?
YES - System performing to specification at this time. Clear the DTC
NO - Go to the applicable troubleshooting procedure.