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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 52 (ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.2L)DIAGNOSTIC TESTSDTC P1441: EVAP SYSTEM FLOW DURING NON-PURGEDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Diagnostic Procedures

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Is DTC P0452 or P0453 also set? If yes, see DTC P0452: FUEL TANK PRESSURE SENSOR - LOW VOLTAGE  or DTC P0453: FUEL TANK PRESSURE SENSOR - HIGH VOLTAGE  . If no, go to next step.
  3. With a scan tool, seal the EVAP system. Start the engine. Increase the engine idle to 1200-1500 RPM. Observe the FTP sensor with a scan tool. Is the FTP sensor near 0 in. Hg (0 in. H2O)? If yes, go to next step. If no, see DIAGNOSTIC AIDS  .
  4. Turn the ignition OFF. Disconnect the EVAP canister purge valve harness connector. Remove and then install the fuel fill cap. With a scan tool, seal the EVAP system. Start the engine. Increase the engine idle to 1200-1500 RPM. Observe the FTP sensor with a scan tool. Is the FTP sensor near 0 in. Hg (0 in. H2O)? If yes, go to step  7 . If no, go to next step.
  5. Turn ON the ignition, with the engine OFF. Connect a test lamp between the control circuit and the ignition voltage circuit of the EVAP purge valve harness connector. Does the test lamp illuminate? If yes, go to next step. If no, see DIAGNOSTIC AIDS  .
  6. Test the purge valve control circuit for a short to ground. Did you find and correct the condition? If yes, go to step  10 . If no, go to step  8 .
    7. NOTE: Check for carbon release into the EVAP system. If carbon is present, see EVAPORATIVE EMISSION SYSTEM CLEANING in REMOVAL, OVERHAUL & INSTALLATION.
  7. Replace the EVAP canister purge valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  10 .
  8. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  10 . If no, go to next step.
  9. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  10. Connect all EVAP hardware that was previously disconnected. Use a scan tool to seal the EVAP system. Start the engine and idle at 1200-1500 RPM. Observe the Fuel Tank Pressure (FTP) with a scan tool. Is the fuel tank pressure near 0 in. Hg (0 in. H2O)? If yes, go to next step. If no, go to step  3 .
  11. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.