Yukon XL 2500 2WD V8-8.1L VIN G (2004)
2. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data
circuit. The specified procedure will determine the particular condition.
3. This step tests for valid system power moding in all ignition switch positions.
5. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the
available information before tests are performed.
