For 1990-2009 cars

Begin the diagnosis by reviewing the system Description and Operation. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. Refer to Diagnostic System Check - Vehicle , in order to identify the correct procedure for diagnosing the system and where the procedure is located.

The Diagnostic System Check will provide the following information:

• | The identification of the control modules which command the system

• | The ability of the control modules to communicate through the serial data circuit

• | The identification of any stored diagnostic trouble codes (DTCs) and their status