You need to remove the glovebox and kick panel to get to the ECU and the wiring harness.
Use a phillipshead screwdriver to remove the two screws on the glovebox mounting tabs.
Remove the four bolts holding the glovebox reinforcement.
Next you need to remove the clips and bolts holding the kick panel on.
Lower kick panel.
Upper kick panel near the kick panel light.
Done, but don't yank it out...
because you have to disconnect the harness for the kick panel light.
ECU and wiring harness.
Use a phillipshead screwdriver to remove the two bolts holding the ECU to the chassis. This is the lower bolt...
and this is the upper bolt.
Disconnect this brown harness.
Use a 10mm socket to remove the bolt holding the wiring harness to the ECU.
There is another harness that needs to be unplugged here.
There is a fastener on the wiring harness that holds it to the chassis here...remove it.
Use a prybar to remove the rubber stopper on the firewall.
Slowly start pulling the wiring harness through the hole in the firewall.
You may have to go inside and work it through but eventually it comes out.
Done! Upper engine harness. If you plan to have the wiring done through a wiring service you will need your SR, CA, RB, etc. wiring harness and the KA upper engine wiring harness to send out to them.