To find your ignition coil, you'll need to:
1. Identify your F-150's year and engine: This information is crucial. The engine code (e.g., 5.0L V8, 2.7L EcoBoost, 3.5L EcoBoost) is usually found on a sticker under the hood or in the owner's manual.
2. Consult a repair manual or online diagrams: Once you know your year and engine, search for a repair manual specific to your truck (Haynes, Chilton, or a factory service manual are good options). Online resources like diagrams on sites specializing in auto parts (e.g., AutoZone, Advance Auto Parts) can also be helpful. Search for your specific vehicle and look for diagrams showing ignition coil location.
3. Visually inspect: With the hood open, look for a component that resembles a coil or a group of coils, often near the spark plugs. They may be mounted directly on the valve covers or on a separate bracket.
Without knowing the year and engine of your F-150, it's impossible to give a precise location for "ignition coil D".