Test Description
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 2. This step inspects for lack of communication that 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 determines the particular condition.
- 3. The presence of DTCs indicates that the transfer case shift control module has detected a fault. Go to symptoms for other concerns.
- 4. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure compiles all the available information before tests are performed.
- 5. Vehicle speed is provided to the transfer case shift control module via Class 2 and can effect the setting of DTC C0300. Perform the diagnostics for powertrain DTC P0502 and DTC P0503 first.
- 6. Perform diagnostics for DTC C0300 and DTC C0305 first before addressing other DTCs. DTC C0300 and DTC C0305 can be responsible for setting other DTCs.