I have heard "g", "2", and do something with the mouse wheel, but nothing happens. What exactly are you supposed to do?I even go to weapon select and hover on the grenade and press 1 or 2 and nothing happens. And yes, I have grenades.
For me it's mapped to my middle mouse button/scroll wheel (By default I believe not 100% sure ATM).
EDIT: To clarify I just press down my scroll wheel like I want to do universal scroll in a web browser.
You can throw it anytime as long as you have them. It's not like C4 where you have to visually equip it to throw it.
You may have possibly changed it so I would recommend to check your mappings in settings. --- GT: Fission MaiIed (L is i); PSN: FissionXMailed (L is L); BNet: FissionMailD#1973; Steam ID: fissionmailD No "i" in team, but there is in fail.