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Test Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. 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. 5:  This step inspects the EVAP canister vent solenoid valve electrical operation.
  2. 6:  This step inspects for a restricted EVAP canister vent solenoid valve.
  3. 7:  This step tests if the restriction is in the EVAP canister or the vent hose.
DTC P0446

Step Action Values Yes No
Schematic Reference:  Evaporative Emissions (EVAP) Hose Routing Diagram  and  Engine Controls Schematics 
Connector End View Reference:  Powertrain Control Module (PCM) 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 Inspect the evaporative emission (EVAP) system for the following conditions:
Did you find and correct the condition?		 - Go to Step 17  Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the EVAP purge line from the EVAP canister purge solenoid valve. Refer to Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement .
  3. Turn ON the ignition, with the engine OFF.
Is the Fuel Tank Pressure Sensor parameter within the Specified range?		 -1 to +1 in H2O Go to Step 4  Go to Step 10 
4
IMPORTANT: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  1. Turn OFF the ignition.
  2. Connect the EVAP purge pipe.
  3. Connect the J 41413-200  Evaporative Emissions System Tester (EEST) power supply clips to a known good 12-volt source.
  4. Install the J 41415-40  Fuel Fill Cap Adapter to the fuel fill pipe.
  5. Connect the fuel fill cap to the J 41415-40  .
  6. Connect the J 41413-200  nitrogen/smoke supply hose to the J 41415-40  .
  7. Turn ON the ignition, with the engine OFF.
  8. Command the EVAP canister vent solenoid valve closed with a scan tool.
  9. Turn the nitrogen/smoke valve on the J 41413-200  control panel to NITROGEN.
  10. Use the remote switch to pressurize the EVAP system to the first specified value.
  11. Observe the FTP Sensor parameter with a scan tool.
  12. Command the EVAP canister vent solenoid valve open with a scan tool.
Is the Fuel Tank Pressure Sensor parameter less than the second specified value?		 5 in H2O
1 in H2O		 Go to Diagnostic Aids Go to Step 5 
5  Command the EVAP canister vent solenoid valve ON and OFF with a scan tool.
Do you hear or feel the EVAP canister vent solenoid valve click when commanded ON and OFF?		 - Go to Step 6  Go to Step 8 
6  Disconnect the EVAP vent hose from the EVAP canister vent solenoid valve.
Is the Fuel Tank Pressure Sensor parameter less than the specified value?		 1 in H2O Go to Step 12  Go to Step 7 
7  Disconnect the EVAP vent hose from the EVAP canister.
Is the Fuel Tank Pressure Sensor parameter less than the specified value?		 1 in H2O Go to Step 14  Go to Step 13 
8
  1. Disconnect the EVAP canister vent solenoid valve.
  2. Probe the control circuit of the EVAP canister vent solenoid valve with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 9  Go to Step 12 
9 Test the control circuit of the EVAP canister vent solenoid valve for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 17  Go to Step 11 
10 Test for an intermittent and for a poor connection at the fuel tank pressure (FTP) sensor. 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 17  Go to Step 15 
11 Test for an intermittent and for a poor connection at the control module. 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 17  Go to Step 16 
12 Replace the EVAP canister vent solenoid valve. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement .
Did you complete the replacement?		 - Go to Step 17  -
13 Replace the EVAP canister. Refer to Evaporative Emission (EVAP) Canister Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Evaporative Emission (EVAP) Canister Replacement (TrailBlazer, Envoy, Bravada, Rainier) .
Did you complete the replacement?		 - Go to Step 17  -
14 Repair the pinched or restricted EVAP vent hose.
Did you complete the repair?		 - Go to Step 17  -
15 Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 17  -
16 Replace the control module. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 17  -
17
IMPORTANT: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  1. Turn OFF the ignition.
  2. Connect all disconnected components.
  3. Connect the J 41413-200  to the fuel fill pipe.
  4. Turn ON the ignition, with the engine OFF.
  5. Command the EVAP canister vent solenoid valve closed with a scan tool.
  6. Turn the nitrogen/smoke valve on the J 41413-200  control panel to NITROGEN.
  7. Use the remote switch to pressurize the EVAP system to the first specified value.
  8. Observe the Fuel Tank Pressure Sensor parameter with a scan tool.
  9. Command the EVAP canister vent solenoid valve open with a scan tool.
Is the Fuel Tank Pressure Sensor parameter less than the second specified value?		 5 in H2O
0 in H2O		 Go to Step 18  Go to Step 2 
18 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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