Look around in the basement for a sump pump basin, it would have a pump and pipe attached and are usually found in the utility room. If not found, then you only have one in the garage.
In my area, the drain tile system goes all the way around the perimeter of the basement (with tees up to window wells). They would then tie into a pipe going through the basement footing and into the basement sump.
More builders are now installing them outside in a deep pipe or in the window well basin. The garage is also a good location. That way you don't allow outside water into the basement to start with. An insulated cover helps prevent freezing. What this doesn't help is if the basement floods from a pipe burst, etc and there is no pump to get it out unless you have a floor drain in it.
I would assume that your system goes all the way around and luckily you haven't had much rain or have good drainage that keeps most water out. The garage sump pump should be as deep as the basement floor. Contact the builder to be sure. Good luck.