This paper presents a new approach for solving non-linear passive location problems. It is based on a high level interval modeling language named Quimper. Whereas classical passive location resolutions do not provide any guarantee of convergence to a solution, interval analysis, constraint propagation and contractor programming allow us to avoid any approximations and any linearization. Besides, Quimper naturally provides guarantees on location and bounded error. TDOA passive location configurations are discussed to prove Quimper's efficiency.