Look on the firewall just to the center of where the brake unit is mounted, and you'll find a plug that can be cut out and used as a grommet around your power wire. It's hard to see without looking for it Another way to look for it is from inside; look in firewall above gas pedal, about 12" higher. This is what I did. Second way would be to route the wire from battery over top of fender liner to plug located on door jamb just forward of the wiring boot that runs from door to door jamb. Be sure to run the power wire away for any stock wiring as much as possible to avoid picking up inductive noise.