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Home >> GMC >> 2003 >> Jimmy 2D Utility, Part Time, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0351: Ignition Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  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 INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
  3. Turn ignition off. Reconnect the injector harness connector. Disconnect the ICM harness connector. Probe the IC timing control circuit with a Digital Volt-Ohmmeter (DVOM) set to the AC scale. Crank the engine. Observe the voltage. Does the voltage measure 1-4 volts? If yes, go to next step. If no, go to step  6.
  4. Turn ignition off. Probe the ICM ground circuit at the ICM connector with a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step  11.
  5. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit at the ICM harness connector with a test light connected to ground. Does the test light illuminate? If yes, go to step  15. If no, go to step  14.
  6. Turn ignition off. Disconnect the PCM connector. Probe the IC timing control circuit at the PCM connector with a test light connected to battery voltage. Does the test light illuminate? If yes, go to step  12. If no, go to next step.
  7. Turn ignition off. 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  17. If no, go to next step.
  8. Reconnect the PCM connector. Turn ignition on, with engine off. Probe the IC timing control circuit at the ICM harness connector with a DVOM set to the DC scale and connected to ground. Does the voltage measure more than 1.0 volt? If yes, go to step  13. 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  17. If no, go to step  16.
  10. Test for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step  17. If no, go to step  15.
  11. Repair open in the ICM ground circuit. After repairs, go to step  17.
  12. Repair short to ground in the IC timing control circuit. After repairs, go to step  17.
  13. Repair short to voltage in the IC timing control circuit. After repairs, go to step  17.
  14. Repair open in the ignition 1 voltage circuit. After repairs, go to step  17.
  15. Replace ICM. See appropriate REMOVAL & INSTALLATION article. After repairs, go to step  17.
  16. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  17. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start 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.
  18. 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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