on vn - vp where is the "ignition module" located
and what is the main purpose of it
dunno about the ignition module, but the ignition coil is on to p of the dfi module, that could be what you mean, it's the bit with the lead going to it on the front top of the passenger side of your engine.
basically provides current to the spark plugs so the engine can ignite the fuel.
is it possible to replace the crank angle sensor with out removing the harmonic balancer
cos i read that it's right behind it, which is about right
You need to remove the harmonic balancer to remove the crank angle sensor. The harmonic slots into the crank angle sensor and when you remove it be ware of bending the fins on the harmonic. there a tuned distance between the grooves of the crank angle sensor.