For 1990-2009 cars

Begin the system diagnosis with Diagnostic System Check - Vehicle . The diagnostic system check vehicle provides the following information:

• | The identification of the control module or modules 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 identifies the correct procedure for diagnosing the system and the procedure location.

#### Symptoms

When it has been determined through Diagnostic System Check - Vehicle that no DTCs are present, begin symptom diagnosis by reviewing the Transmission Component and System Description . Reviewing the Transmission Component and System Description information enables you to understand the operation of the system. 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 . Symptoms - Automatic Transmission provides common diagnostic categories which relate directly to diagnostic information or procedures.