i just read the answer to your post in another thread in the audio, electrical, and security forum just a few minutes ago... you need to look for where the ecu wiring harness goes through (there should be a rubber grommet)... on my car under the hood it is behind and just to the left (towards the center of the car) of the battery...
Using the instruction for installing the Toyota VIP RS3200 Toyota alarm,we can use the wire-routing method described for running #4AWG or #8AWG wire for an aftermarket audio setup......this works slick as hell and no drilling is required!
Here is what you need to do:
* FOLLOW STEP #2 AND STEP #3 ON THIS PAGE:
Now that you have the outside and inside access to the grommet,
* THEN FOLLOW STEP #3 AND #5 (fig B3) ON THIS PAGE:
Your wires WILL fit in the little hole that is created when you cut off that little nipple from the grommet!