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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 388 (ENGINE CONTROLS SELF-DIAGNOSTICS)PROGRAMMINGCRANKSHAFT POSITION SENSOR
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Crankshaft Position Sensor

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Crankshaft Position Sensor
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For additional diagnostic information, see DTC P0336: CRANKSHAFT POSITION SENSOR CIRCUIT PERFORMANCE  under DIAGNOSTIC TESTS.
  1. Install a scan tool.
  2. With a scan tool, monitor the powertrain control module for DTCs. If other DTCs are set, except DTC P1336, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  3. Select the Crankshaft Position (CKP) variation learn procedure with a scan tool.
  4. The scan tool instructs you to perform the following:
    • Accelerate to Wide Open Throttle (WOT).
    • Release and observe the fuel cut-off for the engine that you are performing the learn procedure on.
    • Engine should not accelerate beyond calibrated RPM value.
    • Release throttle immediately if value is exceeded.
    • Block drive wheels.
    • Set parking brake.
    • Do not apply brake pedal.
    • Cycle the ignition from OFF to ON.
    • Apply and hold the brake pedal.
    • Start and idle engine.
    • Turn A/C OFF.
    • Vehicle must remain in Park or Neutral.
    • The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
      1. Crankshaft Position (CKP) sensor activity. If there is a CKP sensor condition, refer to the applicable DTC that set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
      2. Camshaft Position (CMP) sensor activity. If there is a CMP sensor condition, refer to the applicable DTC that set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
      3. Engine Coolant Temperature (ECT). If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
  5. Enable the CKP system variation learn procedure with a scan tool.
    6. NOTE: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.
  6. Accelerate to Wide Open Throttle (WOT).
  7. Release when the fuel cut-off occurs.
  8. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P1336 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P1336 failed or did not run, see DTC P1336: CRANKSHAFT SYSTEM VARIATION NOT LEARNED . If any other DTCs set, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  9. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
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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.