I would agree that wiring harnesses in newer Toyotas aren't what they used to be (beginning with the 6 series). After checking the obvious (fuse box. etc, ) I'd unwrap the suspected wiring harness just to be sure. I had an intermittant short in a 6 series that turned out to be wiring worn thru inside the wiring harness. ( the way Toyota splits off pigtails is sad. They removed a little of the insulation on the main wire, laid the pigtail on that wire & then used a metal band (about 1/8 in diameter) & crimped the 2 together- no insulation or anything covering this junction- then they just surrounded this juntion with the other wires in the harness. Needless to say, the wires surrounding this juntion eventually wore thru & shorted thanks to the uninsulated juction.)

This was a factory wire harness which had not been altered- I worked on the truck since new. That was the beginning of the end for my respect for Toyotas.