Does the rider need to expend an action to ride a horse?

Question

During the last session of my d20 Modern game, I had a player and NPC on horseback, and I realized that the rules aren't clear on the Action breakdown between horse and rider.

Ride Animal doesn't state whether or not controlling the animal takes an Action, just that you can do all sorts of reactionary stunts to keep your hands free or take cover. And it also doesn't say whether or not the horse's movement is tied to the horse's actions or not.

So, in short, how does this work? Does the horse decide "I'm using a Full Action to move x4 my base movement", and the rider gets their standard Move Action and Attack Action, or does the rider have to use a Move action to control the horse? Does the rider have to use a Full Action to get the horse to do an all-out move?

Related: the chase/driving rules do state that controlling a vehicle is a Move action. I chose to do that to keep the game moving at the time, but I'd like to know the "real" answer. IE, Rules as Written, if there is one.

Answer 1

Mounts use the actions of the rider.

Ride (Dex)

Check: Typical riding actions don’t require checks. A character can saddle, mount, ride, and dismount without a problem. Mounting or dismounting an animal is a move action. Some tasks, such as those undertaken in combat or other extreme circumstances, require checks. In addition, attempting trick riding or asking the animal to perform an unusual technique also requires a check.

Fight while Mounted (DC 20): While in combat, the character can attempt to control a mount that is not trained in combat riding (see the Handle Animal skill). If the character succeeds, he or she uses only a move action, and the character can use his or her attack action to do something else. If the character fails, he or she can do nothing else that round. If the character fails by more than 5, he or she loses control of the animal.

For animals trained in combat riding, the character does not need to make this check. Instead, the character can use his or her move action to have the animal perform a trick (commonly, to attack). The character can use his or her attack action normally.

Time: Ride is a move action, except when otherwise noted for the special tasks listed above.

Source: d20 Modern SRD