Service Information

Orlando

Symptoms - Data Communications

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

Perform the Diagnostic System Check - Vehicle before using the symptom tables in order to verify that all of the following are true:

•	There are no DTCs set.

•	The control modules can communicate via the serial data links.

Review the system operation in order to familiarize yourself with the system functions. Refer to Data Link Communications Description and Operation .

•	Inspect for aftermarket devices which could affect the operation of the systems. Refer to Checking Aftermarket Accessories .

•	Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

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

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 High Speed GMLAN Device

•	Scan Tool Does Not Communicate with Low Speed GMLAN Device

•	Scan Tool Does Not Communicate with Chassis High Speed GMLAN Device