When you’re adding audio amps or trailer wiring, adding fuse and power wire through the bulked to the battery can present a major obstacle. Rather than following the route of other wire bundles I chose to follow the route of the hood release cable. It is relatively simple and uncluttered, and you needn’t worry about fishing probes nicking other wires. You will need to remove the left front wheel and all of the fasteners on the back half of the plastic liner over the wheel. The hood release cable is easy to find, and passes solo through a rubber grommet with enough space in the thin grommet to poke a small hole through followed by a semi rigid fish wire into the area to the left of the parking brake foot pedal. I pulled a 12 ga power wire with a piece of multi stranded copper wire of a similar diameter butted together with a couple of wraps of electricians tape so there was no significant bulge. It passed through the grommet easily with no tearing. The path from there to the battery post is clear, following the lead of the hood release cable. Photos are from 2020 Prius Prime. I suspect other Prius models will offer a similar opportunity.
Yes, our 2013 Prius and 2014 Avalon hybrid were both rear battery. Wiring those for trailers is that much easier. Perhaps it’s only the plug-ins, with their larger battery pack in the rear, that have the 12v forward. Prior to those vehicles I had a 2005 Civic hybrid, where I first learned to follow the hood cable to the battery.
