I have a question that that the main rulebook could not clarify, or atleast i could not find my answer in it. My question is this, can a player choose to set the timing to be on impact so that if the grenade is thrown it is resolved in the same pass? The problem is that under timing of grenades on SR3 pg 118 it states that grenades thrown explode in the throwers next initiative phase,however, on pg 282 of the SR3 it states that grenades may be set to explode on impact or have a range of timing that of 2seconds to 2 minutes. Now on pg 118 under timing of grenades, are the rules represented there are for the 2 seconds that a grenade can be set too or does it just really mean for grenades set on impact?Also do minigrenades work exactly as thrown grenades or do they just simply explode when it reaches its target?

Mini-grenades don't explode when they reach their target without a weapon accessory called something like grenade-link timer or somesuch.

I believe the grenades exploding on your next initiative pass rule is essentially "on impact". The timer rules are basically to set the grenade up as a booby trap, and I think the two triggering conditions for that are release of pressure or an electrical current.

Mini-grenades are functionally the same as grenades in terms of damage dealt. They must be launched from a grenade launcher, and won't detonate if they land within 5 meters. They have 3d6 meter scatter instead of 1d6 meter scatter for normal grenades, or 2d6 for aerodynamic. However, if you have a smartlink 2 system, rangefinder, and grenade link, you can time the minigrenade to detonate at a certain distance. The game effects are to drop its scatter from 3d6 to 1d6 and it will detonate in the same combat phase it was launched in.