A Symptoms - Data Link Communications

IMPORTANT: The following steps must be completed before using the symptom tables.

1. Perform the applicable diagnostic system check before using the Symptom Tables in order to verity that all of the following are true:
^ There are no DTCs set.
^ The control module(s) can communicate via the serial data link.
2. 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 vehicle systems. Refer to Checking Aftermarket Accessories in Diagrams.
^ 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 Diagrams.

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
^ Scan Tool Does Not Communicate with Keyword Data Line.