Engine bay wiring pics

Ok. So I am ready to tackle the engine bay wiring harness that was in a box ,in the trunk when I got the car. Spread the harness out on the floor and have most of it figured out. But I have a few questions,
Immediately Off the firewall connection there is a large main harness and and small one ( see pics ) what / where does the small harness go to ?
Does anyone have good pics of the wiring harness in the engine bay ? thanks