For 1990-2009 cars

Begin the system diagnosis with Powertrain On Board Diagnostic (OBD) System Check (2.4L) or Powertrain On Board Diagnostic (OBD) System Check (3.4L) in Engine Controls. The Powertrain OBD System Check provides the following information:

• | The identification of the control module(s) which commands the system.

• | The ability of the control module(s) to communicate through the serial data circuit.

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

The use of the Powertrain On Board Diagnostic (OBD) System Check (2.4L) or Powertrain On Board Diagnostic (OBD) System Check (3.4L) in Engine Controls identifies the correct procedure for diagnosing the system and the procedure location.

#### Symptoms

When it has been determined through Powertrain On Board Diagnostic (OBD) System Check (2.4L) or Powertrain On Board Diagnostic (OBD) System Check (3.4L) in Engine Controls 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 the Symptom Diagnosis table. The Symptom Diagnosis table provides common diagnostic categories which relate directly to diagnostic information or procedures.