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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Chevrolet Malibu Classic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the generator harness X1 connector.
  2. Ignition ON, connect a test lamp to battery positive voltage and repeatedly probe the generator field duty cycle signal circuit, harness side terminal 2, while monitoring the GEN-F Terminal Signal Parameter in the ECM data list with a scan tool. Verify that the scan tool parameter changes from 0 percent to greater than 95 percent.
    • If the GEN-F Terminal Signal scan tool parameter was not affected by the test lamp, then test the generator field duty cycle signal circuit for a short to voltage, a short to ground, a high resistance, or an open circuit. If OK, then replace the ECM.
  3. If the circuit tests normal, then replace the generator.
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