Sierra 1500 2WD V6-4.3L VIN X (2004)
Steps 5-7
The numbers below refer to the step numbers on the diagnostic table.
4. 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.
5. The symptom list in Symptoms will determine the correct diagnostic procedure to use.
6. 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.