P0448
DTC P0448 EVAP. EMISSION SYSTEM-VENT CONTROL CIRCUIT SHORTEDComponent Location:
GENERAL DESCRIPTION
The vent valve is a device that is designed to dose off the fresh air inlet to the canister. Currentness valve designs are powered closed. An electrically operated vent valve solenoid is required for OBD II compliant evaporative systems. Normally the vent valve is in the open (unpowered)state, but to control the vacuum levels in the fuel tank the EVPD will command the vent valve solenoid to the closed position. This controlled vacuum level will allow the EVPD to determine the integrity of the evaporative system.
The vent valve orifice is much larger than the purge valve orifice or purge lines so that when the vent valve is open, the purge flow is not restricted. The fresh air inlet in the vent valve solenoid is normally filtered with a serviceable dust filter that helps to prevent contaminants from being drawn into the evaporative system (e.g. water, salt, silica, etc.).
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:
Schematic Diagram:
ACTUATION TEST
1. Connect Scantool on the DLC( Data Link Connector).
2. Perform Actuation Test for Canister Vent Solenoid Valve with Scantool.
3. Check that clicking sound can be heard by actuation test.
4. Is the CCV normal ?
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, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to "Terminal and Connector Inspection" 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 "1" 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 "1" 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 (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.
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. 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 tests have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable trouble shooting procedure.
NO: System is performing to specification at this time.