To identify them correctly, you need to consult:
1. Your vehicle's repair manual: This is the most reliable source. The manual will have diagrams showing the exact location and numbering of the ignition coils.
2. A wiring diagram: These diagrams show the electrical connections, and often include a clear labeling of the coils. You can often find these online through forums dedicated to your specific F-150 year and engine, or via online auto parts websites (often requiring a vehicle identification number (VIN)).
3. Visual inspection (with caution): Sometimes, the coil packs themselves might have numbers stamped on them, or the wiring harness might have labels near the connectors. However, this is *not* a reliable method, and should only be used as a last resort, after consulting the repair manual or wiring diagram. Misidentifying them can lead to damage.
4. Using a multimeter (advanced): With a multimeter, you could potentially trace the wires back to the ignition control module (ICM) to identify which coil corresponds to which cylinder. This is a more advanced technique and should only be attempted if you are comfortable working with automotive electrical systems. Incorrectly performing this could also damage your vehicle's electrical system.
In short: Don't rely on guesswork. Find your vehicle's repair manual or a wiring diagram specific to your F-150's year and engine to avoid potential damage.
