Test Description

The numbers below refer to the step numbers 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: The symptom list in Symptoms will determine the correct diagnostic procedure to use.
4: The presence of DTCs which begin with "U" indicate that loss of class 2 communications has occurred.

Diagnostic System Check - Driver Information Systems

Step	Action	Yes	No
1	Install a scan tool. Does the scan tool power up?	Go to Step 2	Go to Scan Tool Does Not Power Up in Data Link Communications
2	Turn the ignition ON, with the engine OFF. Attempt to establish communication with the following control modules: Engine Control Module (ECM) Instrument Panel Cluster (IPC) Radio Does the scan tool communicate with the control modules listed above?	Go to Step 3	Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
3	Select the display DTCs function on the scan tool for the following modules: Engine Control Module (ECM) Instrument Panel Cluster (IPC) Radio Does the scan tool display any DTCs?	Go to Step 4	Go to Symptoms - Instrument Panel, Gages and Console
4	Does the scan tool display any other DTCs which begin with a "U"?	Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications	Go to Step 5
5	Does the scan tool display DTC B1000, B1004, B1007, B1009, B1372, B1382, or B1390?	Go to Diagnostic Trouble Code (DTC) List in Body Control Systems	Go to Step 6
6	Does the scan tool display B1327, B1328, B1513, B1514, P0562, P0563, P0615, P0616, P0617, P0625, P0626, P2500, or P2501?	Go to Diagnostic Trouble Code (DTC) List in Engine Electrical	Go to Diagnostic Trouble Code (DTC) List