* Under the hood, in the Power Distribution Box (PDB): This is the most common location. The PDB is usually located near the battery, often on the passenger side fender well. The relay itself is usually a standard automotive relay and may not be clearly labeled "EEC." You'll likely need to consult a wiring diagram for your specific truck (available online or at a parts store) to identify it. Look for a relay that's connected to the Powertrain Control Module (PCM).
* Inside the cab, under the dash: Less common, but possible. This location is less frequent for the main EEC relay, but some smaller relays associated with the EEC system might be found here in the fuse box.
To find it definitively:
1. Consult your owner's manual: This is the best place to start. It should have a diagram of the fuse and relay boxes.
2. Use a wiring diagram: A wiring diagram for your specific 1996 Ford F-150 (including engine size) is crucial. You can often find these online through forums dedicated to Ford trucks or at auto parts stores. These diagrams will show you exactly where the EEC relay is and what it connects to.
3. Look for a relay that's consistently mentioned in relation to the PCM or the computer in online forums/repair manuals: Searching online for "1996 Ford F-150 EEC relay location [your engine size]" will probably yield helpful results from other owners who've dealt with the same issue.
Remember to disconnect the negative battery terminal before working on any electrical components. Incorrectly identifying and swapping relays can cause damage to your vehicle.
