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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 70 (ENGINE CONTROLS SELF-DIAGNOSTICS - 4.3L)DIAGNOSTIC TESTSDTC P0351: IGNITION CONTROL CIRCUITDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Diagnostic Procedures

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Sonoma, 2002 GMC Safari, 2002 GMC Jimmy, 2002 Chevrolet S10 Pickup, and 2002 Chevrolet Blazer. 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. Clear the DTCs. Disconnect the injector harness connector. Crank the engine for 15 seconds. Does DTC P0351 set? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  3. Turn the ignition OFF. Reconnect the injector harness connector. Disconnect the ICM harness connector. Probe the IC timing control circuit with a Digital Multimeter (DMM) set to the AC scale. Crank the engine. Observe the voltage. Does the voltage measure 1-4 V? If yes, go to next step. If no, go to step  6.
  4. Turn OFF the ignition. Probe the ICM ground circuit at the ICM connector with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to next step. If no, go to step  10.
  5. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit at the ICM harness connector with a test lamp connected to ground. Does the test lamp illuminate? If yes, go to step  14. If no, go to step  13.
  6. Turn OFF the ignition. Disconnect the PCM connector. Probe the IC timing control circuit at the PCM connector with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to step  11. If no, go to next step.
  7. Turn OFF the ignition. Test for an open in the IC timing control circuit between the PCM and the ICM harness connector. Did you find and correct the condition? If yes, go to step  16. If no, go to next step.
  8. Reconnect the PCM connector. Turn ON the ignition, with the engine OFF. Probe the IC timing control circuit at the ICM harness connector with a DMM set to the DC scale and connected to ground. Does the voltage measure more than 1.0 V? If yes, go to step  12. If no, go to next step.
  9. Inspect for poor connections at the harness connector of the PCM. Does you find and correct the condition? If yes, go to step  16. If no, go to step  15.
  10. Repair the open in the ICM ground circuit. After repairs, go to step  16.
  11. Repair the short to ground in the IC timing control circuit. After repairs, go to step  16.
  12. Repair the short to voltage in the IC timing control circuit. After repairs, go to step  16.
  13. Repair the open in the ignition 1 voltage circuit. After repairs, go to step  16.
  14. Replace the ICM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  16.
  15. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  16. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  17. 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.