Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , and Lubrication Description in Engine Mechanical - 6.6L Unit Repair Manual, and the Drive Belt System 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 to you by the customer is normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct procedure for diagnosing the system and where the procedure is located.