Wiring diagrams for a Ford Premium (JBL) sound system, as with any vehicle sound or entertainment system, are printed in the factory authorized repair manual along with other vehicle wiring schematics. Finding the diagram that you need requires you locate a copy of the repair manual or the standalone entertainment system diagrams for your specific Ford vehicle (model and year). Thankfully, multiple free and fee-based services offer access to this information.
Check with an auto-related membership club. Many offer special benefits that not only include repair advice, but also factory vehicle repair/wiring diagrams. Check Ford-specific clubs, entertainment system or "car audio" clubs and/or retail parts store clubs.
Visit a library. Check the automobile repair section for factory manuals by vehicle type that include entertainment system wiring diagrams.
Go to an audio store that specializes in entertainment systems for a wide variety of vehicles and ask if the store sells wiring diagrams/repair manuals.
Purchase a wiring diagram or repair manual from a Ford "factory authorized" company.
