Handbook 652 Body Electrical Diagnosis System Outline Some system circuit diagrams include a System Outline. When troubleshooting a circuit, you should always review the System Outline (when it is available) to help you understand how the circuit works. This is especially important in circuits with logic components because the internal logic is not always obvious from the circuit diagram. NOTE When a System Outline is not provided, use the system description in the Repair Manual or New Car Features manual. Service Hints The system circuit diagram frequently includes Service Hints that can be helpful in diagnosis. 66 Technical Training