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Testing the Serial Data Circuit for an Open/High Resistance

  1. Ignition OFF, disconnect the appropriate harness connectors at the BCM.
  2. Install a 3A fused jumper wire between the disconnected BCM connector DLC terminal and a class 2 serial data circuit that is not communicating.
  3. Ignition ON, verify the scan tool communicates with the control modules connected to the class 2 serial data circuit.
    • If any control module does not communicate, test each section of the serial data circuit for an open/high resistance. If the circuits test normal, replace the control module that does not communicate when connected.
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