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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 529 (Charging System) >> Diagnostic Tests >> DTC P0622: Out Of Range Duty Cycle Signal >> Diagnostic Procedure

Diagnostic Procedure

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. If diagnostic system check was not performed, perform ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK  under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC). See COMPONENT LOCATIONS  . Start engine. Using scan tool, observe GEN F-Terminal parameter in Powertrain Control Module (PCM) data list. If scan tool indicates GEN F-Terminal parameter is 5-95 percent, go to next step. If scan tool does not indicate GEN F-Terminal parameter is 5-95 percent, go to step  4 .
  3. With the scan tool command the generator OFF. If scan tool indicates GEN F-Terminal parameter is zero percent, problem is intermittent. Check wiring and connections. If scan tool does not indicate GEN F-Terminal parameter is zero percent, go to next step.
  4. Turn OFF the ignition. Disconnect the generator connector. Connect test light to battery positive voltage. Turn ON the ignition, with the engine OFF. Probe the F-Terminal in the generator connector. See WIRING DIAGRAMS  . Observe the GEN F-Terminal Signal parameter in the PCM data list. If scan tool indicates GEN F-Terminal parameter is 100 percent, perform TEST A: CHARGING SYSTEM TEST  under SYSTEM TESTS. If scan tool does not indicate GEN F-Terminal parameter is 100 percent, go to next step.
  5. Test Gray wire for short or open between generator harness connector terminal "C" and PCM harness connector C2 terminal No. 51. See WIRING DIAGRAMS  . If problem exists, repair as necessary. After repair, go to step  8 . If problem does not exist, go to next step.
  6. Inspect PCM harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step  8 . If problem does not exit, go to next step.
  7. Replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Program PCM. After repair, go to next step.
  8. Review and record scan tool Fail Records data. Using scan tool, clear DTCs. Operate vehicle within Fail Records conditions as noted. Using scan tool, observe Specific DTC information for DTC P0622. If scan tool indicates DTC P0622 failed this ignition, repeat test beginning at step  2 . If scan tool indicates DTC P0622 passed this ignition, system is okay.
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