Diagnostic System Check - HVAC System - Automatic

Steps 1-6:

The number(s) below refer to the step number(s) on the diagnostic table.
2. Lack of communication may be due to a partial or total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
4. The presence of DTCs which begin with "U" indicate some of the modules are not communicating.