There haven't been too many really watershed eras in the history of the automobile -- times that forever changed what the car would later be. In fact, you could make the argument that there was really only one after the 1930s: about 1975 to the turn of the century. It was in this era that old-school iron became the computer controlled, emissions conscious, crash tested, decent riding, sophisticated vehicles of today. Ford had not a little to do with driving automotive development during this period, with the OBD-II 1996 Explorer being one of the greatest turning points of all.
Use a ratchet and socket to remove the negative battery cable and set it aside. Normally you'd want to use a memory saver to retain the factory programming, but since you're removing the computer, there's no point in using a memory saver.
Look under the hood on the firewall, high and just to the right of center. You'll see the large wiring harness loom dissappear into a cover on the firewall -- the computer is under this cover. You'll see a single nut holding the cover to the firewall. Remove it, and pull the cover off.
Remove the bolt holding the wiring harness plug to the computer, and unplug the wiring harness. Pull it and the outer cover to the side. You can now remove the second cover surrounding the perimeter of the computer. Remove the two nuts you see there, and pull the cover off.
Grasp the ECM, pull it toward the front of the vehicle and out of the recess. There's enough room to get the computer out over the engine's manifold runners. To install a new computer, slide the new unit in as you pulled the old one out.
Install the retaining plate and tighten its nuts hand tight. Plug the wiring harness in and install the retaining bolt. Install the outer cover and its retaining nut. Install the negative battery cable. Start the engine, and test drive the Explorer. The computer shouldn't require any relearn procedure; the factory settings in the new computer will suffice until it adjusts to the sensor inputs from your truck.
