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Circuit/System Testing

  1. With ignition ON, and the engine OFF.
  2. Disconnect the generator harness and measure the voltage of the generator turn on signal circuit, should read near 0 volt.
    • If greater than 0 volt, test the generator turn on signal circuit for a short to voltage, or replace the ECM.
  3. With ignition ON, and the engine running, the voltage of the generator turn on signal circuit, should read near 5 volts.
    • If no voltage is measured, test the generator turn on signal circuit for a short to ground, an open or a high resistance or replace the ECM.
  4. Go to Charging System Test .