In D&D3.5, traps could only be found if the character used the Search skill within 10 feet of the trap, but Pathfinder did not carry this rule over. Pathfinder uses perception to allow characters to search for traps. Unfortunately, the rules do not specify how the traps are perceived (sight? sound? smell? touch?). This has led some players to the conclusion that their characters search for traps by only using perception by sight and at any distance.
All the rules for Trap-Finding from Pathfinder apply in addition to the following:
*Characters may roll a normal Perception check, Take10, or Take20 to find traps.
*Most traps can only be detected if a character is within 10 feet from the trap or trigger.
*Very small traps and triggers may only be detected while in the same square (poison needle)
*Larger traps may be detected from as far away as 50 feet (pits, rock falls, etc)
*It takes a full-round action to search a 5-foot-by-5-foot wall.
*It takes 2 minutes to search a 5-foot-by-5-foot wall using Take20.
*It is assumed that a character is using all senses to detect traps.