The radio is the only module connected to the class 2 serial data circuit, connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.
Step  | Action  | Yes  | No  | 
|---|---|---|---|
Schematic Reference: Data Link Connector Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems  | |||
1  | Did you perform the Diagnostic System Check - Vehicle?  | Go to Step 2  | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information  | 
2  | 
 Are any DTC's retrieved from any module?  | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information  | Go to Step 3  | 
3  | 
 Is the resistance within the specified range?  | Go to Step 5  | Go to Step 4  | 
4  | Test the class 2 serial data circuit for a short to voltage, short to ground, or an open high resistance. Did you complete the repair?  | System OK  | --  | 
5  | Replace the radio. Did you complete the repair?  | System OK  | --  |