A Diagnostic System Check

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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. Tests for the presents of DTCs. The presence of DTCs indicates that the transfer case shift control module has determined that a fault has taken place within its system.
4. 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.
5. The presence of DTCs which are related to the powertrain's vehicle speed sensor has the potential of setting transfer case codes due to information that is shared by the transfer case shift control module via Class 2. These codes should be repair first.
6. The presence of DTC C0300 or C0305 should be repaired before addressing other transfer case DTCs.