Where is the wiring harness located on a 2008 ford focus?

Where is the wiring harness located on a 2008 ford focus?

In the car.

The wiring harness. Hmm, the wiring harness. Which wiring harness? For what?

Yor is correct, the wiring harness is everywhere. It starts with the heavy cables to the battery, includes the fuse box, and goes to all the tail lights, dome light, etc.

Underneath the switch, a little to the left.

Throughout the car, from front to rear.

There are a few. They are separate from one another. And installed throughout the vehicle. Some meet at the power distribution center.
Others tag on at the end of the one that supplies them.
You may want to clarify what circuit and or connector you are working on. Ford can supply some repairs without complete replacement.
The circuits are numbered, the hardshell connectors are numbered. The service manual and the EVTM lead you right to your answers if you have a question.