But can I order my subordinate Corps comander to keep his cavalry with him after a succesful fight and not let it pursue the enemy? I mean if I can see that the retreating enemy is a trap and the cavalry would fall into that trap if it pursues the enemy I would want to give a my marechal a warning if not an order to halt his cavalry.He may do it on his own,but perhaps he cannot see the danger from his position,and since I have an overall view of the battlefield I can better estimate the danger and tell him how to act.
A battlefield is a large space with little place to hide corps in order to make ambush. Besides, cavalry is hard to ambush because of its mobility. So, you talk about a situation that rarely exists. Now if it does, it depends on orders you previously gave to your cavalry. When you give orders you determine a line of deployment, the corp don't go further but cavalry may engage any ennemy cavalry unit that comes within charge distance (this attitude is moderate by the degree of agressivity you gave to units cavalry) but when the fight is over, engaged units come back to previous line of deployment. Other case, if you ordered a cavalry corp to reach a deployment line and for any reason you want it to stop then you must send an aide de camp to order it to stop.
So, to avoid ambush I advise you to send cavalry reconnaissances to suspect places before moving your corps and to chose before the beginning of the game the right agressivity. In my opinion, the best is high for light cav, neutral for line cav and low for heavy. Despiste these good measures, like in real life , a cavalry corp commander will not let an ennemy cavalry taunts him without launching one or two regiments to punish it.