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Home >> Chevrolet >> 2004 >> Epica LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 2.5L (LBK) DTC P1172 Or P1175 To DTC P1673 >> DTC P1449 >> Test Description

Test Description

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

  1. 4:  This test determines if the FTP sensor is operating correctly.
Step Action Values Yes No
Schematic Reference:  Evaporative Emissions (EVAP) Hose Routing Diagram 
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 Did DTC P0444, P0445, P0447, P0448, P0451, P0452, P0453, or P0454 set? - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3 Inspect the EVAP system for the following conditions:
Did you find and correct the condition?		 - Go to Step 14  Go to Step 4 
4 
  1. Disconnect the purge line from the EVAP purge valve.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the fuel tank pressure parameter.
Does the scan tool indicate fuel tank pressure near the specified value?		 0 in H2O Go to Step 5  Go to Step 8 
5
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. Reconnect all previously disconnected hardware.
  3. Connect the J 41413-200  power supply clips to a known good 12-volt source. See Special Tools .
  4. Remove the fuel tank filler cap.
  5. Install the J 41415-40  to the fuel fill pipe.
  6. Install the fuel tank filler cap to the J 41415-40  .
  7. Turn the nitrogen/smoke valve on the EEST to nitrogen.
  8. Turn ON the ignition, with the engine OFF
  9. With a scan tool, seal the EVAP system.
  10. Use the remote switch to activate the J 41413-200 and pressurize the fuel tank with nitrogen.
  11. Observe the FTP sensor parameter on the scan tool and continue to introduce nitrogen until the first specified value is indicated.
  12. With a scan tool command the EVAP vent valve OFF.
Does the scan tool indicate fuel tank pressure near the second specified value?		 5 in H2O
0 in H2O		 Go to Diagnostic Aids Go to Step 6 
6 Disconnect the EVAP vent hose from the EVAP vent valve.
Does the scan tool indicate fuel tank pressure near the specified value?		 0 in H2O Go to Step 10  Go to Step 7 
7 Disconnect the EVAP vent hose from the EVAP canister.
Does the scan tool indicate fuel tank pressure near the specified value?		 0 in H2O Go to Step 13  Go to Step 11 
8 With a scan tool, observe the fuel tank pressure sensor voltage.
Is the FTP sensor voltage more than the specified value?		 4.3 V Go to DTC P0453 Go to Step 9 
9 Test for poor connections at the harness of the fuel tank pressure 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 14  Go to Step 12 
10 Replace the EVAP vent valve.
Did you complete the replacement?		 - Go to Step 14  -
11 Replace the EVAP canister.
Did you complete the replacement?		 - Go to Step 14  -
12 Replace the fuel tank pressure sensor.
Did you complete the replacement?		 - Go to Step 14  -
13 Repair for a blockage in the EVAP vent hose.
Did you complete the repair?		 - Go to Step 14  -
14
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. Reconnect all previously disconnected hardware.
  3. Connect the J 41413-200  power supply clips to a known good 12-volt source. See Special Tools .
  4. Remove the fuel tank filler cap.
  5. Install the J 41415-40  to the fuel fill pipe.
  6. Install the fuel tank filler cap to the J 41415-40  .
  7. Turn the nitrogen/smoke valve on the EEST to nitrogen.
  8. Turn ON the ignition, with the engine OFF
  9. Command the EVAP vent solenoid closed with a scan tool.
  10. Use the remote switch to activate the J 41413-200 and pressurize the fuel tank with nitrogen.
  11. Observe the FTP sensor parameter on the scan tool and continue to introduce nitrogen until the first specified value is indicated.
  12. With a scan tool command the EVAP vent valve OFF.
Does the scan tool indicate fuel tank pressure near the second specified value?		 5 in H2O
0 in H2O		 Go to Step 15  Go to Step 3 
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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