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Home >> Cadillac >> 2012 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1427 (Battery, Charging System And Starting System) >> Diagnostic Information and Procedures >> DTC P0621 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the generator.
  2. Ignition ON, engine OFF, test for less than 1 volt between the generator turn on signal circuit terminal 1 X1 and ground.
    • If greater than the specified range, test the generator turn on signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Engine running, command the GEN L-Terminal ON to 85% with a scan tool. Test for greater than 3.5 volts between the generator turn on signal and ground.
    • If less than the specified range, test the generator turn on signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. If the circuit tests normal, replace the generator.
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