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Home › Saturn › 2002 › L300 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0621: Generator "L" Terminal Circuit › Diagnostic Procedures

Diagnostic Procedures

  1. Turn ignition off for 10 seconds. Turn ignition on, with engine off. Using scan tool, monitor status of DTC P0621 LAST TEST. If DTC P0621 LAST TEST did not fail, problem is intermittent. See DIAGNOSTIC AIDS  . If DTC P0621 LAST TEST failed, go to next step.
  2. Start engine. Turn off all accessories. Using scan tool, monitor IGNITION 1 voltage in ECM data table. If voltage is more than 13 volts, system is charging. Repair short to voltage in Red wire between generator and ECM. If voltage is not more than 13 volts, go to next step.
  3. Turn ignition on, engine off. Using DVOM, measure voltage on generator connector ring terminal (Red wire). If battery voltage is present, check generator connector. Repair as necessary. If connector is okay, replace generator. If battery voltage is not present, check for open in Red wire between ECM and generator. If wire is okay, replace ECM.
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