I have written these as an alternative to removing
the driver's side kick-panel and the parking brake/hood release support
bracket to get to the ECU on my 1993 F150. That method looked way too involved,
so I decided to remove the ECU through the firewall from the engine compartment.
Here's how I did it:
If you try these, you do so at your own risk! You
can't blame me if something goes wrong or it doesn't work!
DO THIS FIRST !!: Remove the keys from the ignition
and disconnect the battery.
a 10mm socket, disconnect the wiring harness from the ECU
an 11mm open-end wrench (or deep well socket) remove the weatherstrip from
around the ECU. There are two nuts on studs connected to the firewall.
Only the nuts come off. (no jokes about studs & nuts)
a 5.5mm socket, remove the 4 bolts that hold the outside of the plastic
fender-liner above and behind (towards rear of truck) the front tire. The
"inner" bolt with the huge washer is 8mm and is actually behind the tire-
towards the engine.
You're not done yet. There's still one more 5.5mm
bolt under the truck- behind the wheelwell.
the ECU out the "front" of the firewall. You'll have to push the plastic
fender liner (that you partially unbolted in the above steps) towards the
front of the truck to squeeze the ECU out. Since I was working by myself,
this is where I used the pry bar. I used the metal "lip" of the fender
as a fulcrum to push the plastic out of the way. Be sure to protect the
paint with a rag or something wrapped around the bar!!
ECU is out. Not very impressive considering the work it took to get it
end opposite the wiring harness connector is taped with a "warning" label.
The ECU code is also shown here. I'm glad it matched the one on the door
the tape and you'll see the edge connector. Clean this really, really good.
I disassembled the ECU with T10 & T12 "torx" screwdrivers then used
cotton swabs & rubbing alcohol to remove the white grease that is on
the connector. My ECU did not have any other coatings (some have a clearcoat
under the layer of grease). I used a little "emory" cloth to shine up the
contacts, then installed the chip.