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Test Description

The number below refers to the step number on the diagnostic table.

  1. 2:  This step determines if a condition exists. An audible click should be heard when the EVAP canister vent valve is commanded ON and OFF. Repeat the commands as necessary.
DTC P0448 Evaporative Emission (EVAP) Vent Solenoid Control

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Command the evaporative emission (EVAP) canister vent valve ON and OFF with a scan tool.
Does the EVAP canister vent valve turn ON and OFF?		 Go to Step 3  Go to Step 4 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 Go to Step 4  Go to Diagnostic Aids
4
  1. Turn OFF the ignition.
  2. Disconnect the EVAP canister vent valve harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the control circuit of the EVAP canister vent valve to the engine control module (ECM) housing.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 6 
5
IMPORTANT: The control circuit for the solenoid is pulled-up to voltage within the ECM. 3.9 volts on the control circuit is normal.
Test the control circuit of the EVAP canister vent valve for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 Go to Step 10  Go to Step 7 
6 Test for shorted terminals and for poor connections at the EVAP canister vent valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 10  Go to Step 8 
7 Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 10  Go to Step 9 
8 Replace the EVAP canister vent valve.
Did you complete the replacement?		 Go to Step 10  -
9 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 Go to Step 10  -
10
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 Go to Step 2  Go to Step 11 
11 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 Go to Diagnostic Trouble Code (DTC) List System OK
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