I was under my 2008 ford f150 4.6 liter truck today & noticed a loose hose on back drivers side.The rubber hose comes from the axle drivers side & there are 2 rubber hoses side by side one is connected but the other hose has a end like it fits into something but i can't seem to find out where it goes.
Thanks for any help

 

Welcome to the site..

Sounds like the axle vent hose.

Is the loose hose connected 'straight into' the brake line junction block? (2 steel lines extending out along the axle housing, and one rubber brake hose ) The vent hose extends up to the frame and ends in a loop. It keeps pressure from building in the rear axle and failing seals, and also keeps water (water can't run uphill) from entering from the looped end. Some will have an angled ended hose, some a loop and a cap, others just a hose. With the vent up high and looped over, water can't enter during boat launching, high water conditions and such..