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 oft 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
PCM sets DTC P0448 if the PCM detects that the CCV control line is short to ground or short to battery line.
DTC Detecting Condition:
Specification:
Schematic Diagram:
MONITOR DTC STATUS
1. Connect scan tool and select Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History(Not Present) fault"?
NOTE:
1. History (Not Present) fault: DTC occurred but has been cleared.
2. Present fault: DTC is occurring at present time.
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 "Component Inspection" procedure.
COMPONENT INSPECTION
1. Ignition "OFF".
2. Disconnect CCV connector.
3. Measure resistance between terminals 1 and 2 of the CCV connector(Component side).
Specification : Approx. 23.9-26.9 ohms at 20 °C (68 °F)
4. Is resistance within the specification?
YES: Go to next step as below.
NO: Check CCV for contamination, deterioration, or damage. Substitute with a known-good CCV and check for proper operation. If the problem is corrected, replace CCV and then go to Verification of Vehicle Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) 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 Supply Circuit Inspection" procedure.
POWER SUPPLY CIRCUIT INSPECTION
1. Ignition "ON" & Engine "OFF".
2. Measure voltage between terminal 1 of the CCV harness connector and chassis ground.
Specification : Approx. B+
3. Is voltage within the specification?
YES: Go to "Control Circuit Inspection" procedure.
NO: Check for a open in the power supply circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
CONTROL CIRCUIT INSPECTION
1. Check for short to ground in control circuit.
1. Ignition "OFF".
2. Disconnect PCM connector.
3. Measure resistance between terminals 2 of the CCV harness connector and 79 of the PCM harness connector.
Specification : Approx. 0 ohms
4. Is resistance within the specification?
YES: Go to next step as below.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to battery in control circuit
1. Ignition "ON" & Engine "OFF"
2. Measure voltage between terminal 2 of the CCV harness connector and chassis ground
Specification Approx. 0 V
3. Is voltage within the specification?
YES: Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO: Repair as necessary 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. 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.