1. Connect a scan tool to the vehicle.
2. Turn the ignition switch to RUN.
3. Attempt to establish communications with the vehicle.

Does the scan tool communicate with the vehicle?

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Go to Step 2

Go to Scan Tool Does Not Communicate with Class 2 Data Line

Inspect for any communication DTCs. (DTCs that start with the letter U.)

Are any communication DTCs set?

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Go to Diagnostic Trouble Code (DTC) List/Type

System OK