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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 990 (Engine Controls Diagnosis - 4.8L, 5.3L, & 6.0L (DTCS P0449 To P2108)) >> Diagnosis >> DTC P0449 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded.
  2. 5:  This step verifies that the control module is providing ground to the EVAP canister vent solenoid valve.
  3. 6:  This step tests if the EVAP canister vent solenoid valve control circuit is grounded.
DTC P0449

Step Action Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) 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 solenoid valve ON and OFF with the scan tool.
Do you hear or feel a click from the EVAP canister vent solenoid valve when the valve is commanded 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. Turn ON the ignition, with the engine OFF.
  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 Intermittent Conditions
4
  1. Turn OFF the ignition.
  2. Disconnect the EVAP canister vent solenoid valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the batter positive voltage circuit of the EVAP canister vent solenoid valve with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 11 
5 
  1. Connect a test lamp between the control circuit of the EVAP canister vent solenoid valve and battery positive voltage circuit of the EVAP canister vent solenoid valve at the EVAP canister vent solenoid valve harness connector.
  2. Command the EVAP canister vent solenoid valve ON and OFF with a scan tool.
Does the test lamp turn ON and OFF with each command?		 Go to Step 9  Go to Step 6 
6  Does the test lamp remain illuminated with each command? Go to Step 8  Go to Step 7 
7 Test the control circuit of the EVAP canister vent solenoid valve for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
8 Test the control circuit of the EVAP canister vent solenoid valve for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
9 Inspect for poor connections at the harness connector of the EVAP canister vent solenoid valve. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 12 
10 Inspect for poor connections at the harness connector of the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 13 
11
IMPORTANT: If the fuse is open, inspect all related circuits for a short to ground.
Repair the open or short to ground in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.Did you complete the repair?		 Go to Step 14  -
12 Replace the EVAP canister vent solenoid valve. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement (Pickup) or Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement (Pickup - 5.3L (L59) Engine) or Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement (1500 Crew Cab) or Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement (Cab/Chassis) .
Did you complete the replacement?		 Go to Step 14  -
13 Replace the control module. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 Go to Step 14  -
14
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  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 15 
15 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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