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Circuit/System Testing

  1. Using the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
  2. Ignition OFF, disconnect the harness connector of the module that is not communicating.
  3. Ignition ON, verify that a test lamp illuminates between the module voltage circuit and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the faulty module.
  4. Test for less than 5 ohm of resistance between the module ground circuits and ground.
    • If greater than 5 ohm, test the ground circuit for an open/high resistance.
  5. Test for less than 1 ohm of resistance in the Class 2 serial data circuit between the non-communicating module and the module that displays the DTC.
    • If greater than 1 ohm of resistance, test the Class 2 serial data circuit for open/high resistance.
  6. If all circuits test normal, replace the module that is not communicating.
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