Begin the system diagnosis by reviewing the system Automatic Transmission Shift Lock Control Circuit Description . 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 Symptoms - Automatic Transmission Shift Lock Control in order to identify the correct procedure for diagnosing the system and where the procedure is located.