A Symptoms - Data Link Communications

IMPORTANT:
^ The Diagnostic System Check for the system that is malfunctioning must be performed before attempting to use the symptom diagnostics. Refer to Control Module References in Body Control ModuleSystem for the appropriate Diagnostic System Check.
^ Review the system operation in order to familiarize yourself with the system functions. Refer to Data Link Communications Description and Operation.

Visual/physical inspection
^ Inspect for aftermarket devices which could affect the operation of the data link communications/serial data circuits. Refer to Checking Aftermarket Accessories in Diagram.
^ Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent and Poor Connections in Diagram.

Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
^ Scan Tool Does Not Power Up
^ Scan Tool Does Not Communicate with Class 2 Device.