In my experience National RV usually places the pump in the water bay, with the rest of the plumbing, but it can vary by model and floor plan.
Even if you had a schematic, it won't show you where the tubes actually run. To find a leak, just start looking for water where it shouldn't be.
If your "leak" symptom is simply occasional pump cycling when no faucet is open, then it is probably the check valve in the pump itself, allowing water to "leak" back into the fresh tank.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL