Can I wire a trailer brake via existing fuses?

[Drummermonkey]

I have recently found need for, and acquired, a trailer brake unit for my 02 SR5 4WD. I've seen schematics for wiring involving running power through the firewall to the unit, then control wires to the 7 pin connector in the back.
Can I run power from an existing fuses under the dash? I know it's a long shot, but could I take power from one of my 12v plugs in the front? All input is appreciated.

 

[RAD4Runner]

...Can I run power from an existing fuses under the dash? I know it's a long shot, but could I take power from one of my 12v plugs in the front?.

You can but I would not recommend it. Stock fuses are there to protect stock circuits.Trailer lights or poor installs of them are notorious for causing problems.
Best to take power from a separate fuse directly connected to the battery. Inline fuses are inexpensive and easy to work with.
Installing inline fuse directly to battery would require less acrobatics and less effort to do properly than tapping off stock fuse under the dash.
If anything goes wrong with trailer wiring separate fuse may blow; stock circuits keep on working and truck keeps on running.

 

[Drummermonkey]

Noted, thanks