Roadside Attraction

Roadside Attraction is a main quest

After meeting with Joshua Graham at the Dead Horses camp, he first needs the Courier's assistance in finding pre-War tools to help prepare his people. These tools will help Graham and the Dead Horses navigate beyond Zion, should they ever need to leave. The Dead Horses or Sorrows will not go look themselves, because they refuse to enter pre-War buildings.

Detailed walkthrough
The broken compass can be found under one of the skeletons in the crashed scout bus. Once found, one can either leave it, take it in its current condition, repair it (with a Repair check of 30), or repair it with the compass sensor module found near the front of the bus. One can then also take it to a workbench and fix it there. Repairing it will add the compass into the inventory and complete the quest.