Diagnostic Starting Point

ALLISON AUTOMATIC TRANSMISSION

Diagnostic Starting Point - Automatic Transmission
Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check provides the following information:
^ The identification of the control module which commands the system
^ The ability of the control module or modules to communicate through the serial data circuit
^ The identification and status of stored diagnostic trouble codes (DTCs)

The use of Diagnostic System Check - Vehicle in Vehicle DTC Information identifies the correct procedure for diagnosing the system and where the procedure is located.

Symptoms
When it has been determined through Diagnostic System Check - Vehicle in Vehicle DTC Information that no DTCs are present, begin symptom diagnosis by reviewing the Functional Test Procedure. This helps you determine if the condition described by the customer is normal or if a malfunction exists. If it is determined that a malfunction exists, identify the concern by referring to Symptoms - Automatic Transmission. Symptom Related Diagnostic Procedures The Symptoms - Automatic Transmission provides common diagnostic categories which relate directly to diagnostic information or procedures.