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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 0-10 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 0-10 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 or high resistance.
    • If all circuits test OK, replace the control module.
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