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Home >> Cadillac >> 2012 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 785 (Battery, Charging System And Starting System) >> Diagnostic Information and Procedures >> DTC P0621 >> Circuit/System Testing
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Circuit/System Testing

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  1. Ignition OFF, disconnect the harness connector at the generator.
  2. Ignition ON, test for less than 1 volt between the generator turn on signal 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, 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, an open or a high resistance. If the circuit tests normal, replace the ECM.
  4. If the circuit tests normal during the Ignition ON / RUN tests, replace the generator.
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