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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 548 (Charging System) >> Diagnostic Tests >> DTC P0622: Improper Pulse Width Modulated Signal (Diesel Engine) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. If diagnostic system check was not performed, perform ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If diagnostic system check was performed, go to next step.
  2. Test Gray wire for a short or an open between generator harness connector terminal "C" and ECM harness connector C2 terminal No. 52. See WIRING DIAGRAMS  . If problem exists, repair as necessary. After repair, go to step  6 . If problem does not exist, go to next step.
  3. Inspect generator harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step  6 . If problem does not exist, go to next step.
  4. Inspect ECM harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step  6 . If problem does not exist, go to next step.
  5. Replace ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Program ECM. After repair, go to next step.
  6. Review and record scan tool fail records data. Using scan tool, clear DTC's. Start engine. Using scan tool, observe specific DTC Information for DTC P0622 until test runs. If scan tool indicates DTC P0622 passed this ignition, system is okay. If scan tool indicates DTC P0622 failed this ignition, go to step  2 .
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