I don't think there's an option to reveal the map automatically, but there's a simple script function - RevealMap() - that you can put in the module's OnEnter script. You can also put in coordinates and a radius to reveal only a specific region. Here's the source code:
// 515: RevealMap
// Reveals the map at the given WORLD point 'vPoint' with a MAP Grid Radius 'nRadius'
// If this function is called with no parameters it will reveal the entire map.
// (NOTE: if this function is called with a valid point but a default radius, ie. 'nRadius' of -1
// then the entire map will be revealed)
void RevealMap(vector vPoint=[0.0,0.0,0.0],int nRadius=-1);