- Symptoms - Data Communications

Symptoms - Data Communications

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

1. 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. Initial Inspection and Diagnostic Overview

2. Review the system operation in order to familiarize yourself with the system functions. Refer to:

* Body Control System Description and Operation
* Data Link Communications Description and Operation

Visual/Physical Inspection

* Inspect for aftermarket devices which could affect the operation of the systems.
* 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 Conditions and Poor Connections. Component Tests and General Diagnostics

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 High Speed GMLAN Device
* Scan Tool Does Not Communicate with Low Speed GMLAN Device