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Circuit/System Testing

  1. Disconnect the EGR valve harness connector and probe the EGR High Control circuit with a test lamp connected to ground. Command the EGR valve from 0 percent to 10 percent and back to 0 percent. The test lamp should illuminate when commanded to 10 percent.
    • If the test lamp remains illuminated when commanded to 0 percent, test the EGR High Control circuit for a short to voltage.
    • If the test lamp does not illuminate, test the EGR High Control circuit for an open, high resistance, or short to ground.
  2. Connect a test lamp between the EGR High Control circuit and the EGR Low Control Circuit. Command the EGR valve from 0 percent to 10 percent and back to 0 percent. The test lamp should illuminate when commanded to 10 percent.
    • If the test lamp illuminates when commanded to 10 percent replace the EGR valve.
    • If the test lamp does not illuminate, test the EGR Low Control circuit for an open, high resistance.
    • If all circuits test OK, replace the control module.
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