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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Isuzu i-370, 2008 Isuzu i-290, 2008 GMC Canyon, and 2008 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X1 harness connectors at the generator and GBCM.
  2. Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0 percent.
    • If greater than the specified value, test the field duty cycle signal circuit terminal 2 X1 for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Connect a test lamp between the field duty cycle signal circuit terminal 2 X1 of the generator harness and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95 percent.
    • If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Reconnect the GBCM harness connector. Disconnect the test lamp.
  5. Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0 percent.
    • If greater than the specified value, replace the GBCM.
  6. Connect a test lamp between the field duty cycle circuit terminal 2 X1 of the generator harness and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95 percent.
    • If less than the specified range, replace the GBCM.
  7. If the circuit tests normal, replace the generator.
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