How do I see bad guys on Battlefield 3 multiplayer map?

Solution 1:

This has changed a bit for final.

However, Ian Torny recently stated, “To clarify – You will appear on the mini-map for a short time [when you fire an unsuppressed weapon], but you will not be flagged/spotted,” referencing Fredrick Thylander’s statement, “It makes you light up on minimap for a split second. Add silencer to avoid it.”

This is a global change for all multiplayer modes. Basically they are moving a bit more towards the Call of Duty: Modern Warfare behavior.

Solution 2:

The only times you will ever see an opponent on your map is if someone (yourself included) has "spotted" the enemy (default "q" on PC, not sure about console but previously it was "back/select"), or they have fired an unsuppressed weapon very recently.

If someone has spotted an enemy, then they will appear on your map as a small red/orange triangle (or wedge), as well as having a small red triangle above their head.

Team-mates will always appear on your map as cyan triangles.