A formulation is presented for analyzing the dynamic response of an electromechanical ball-in-tube crash sensor (EMS). The response of this type of sensor is affected by the time during which a sensing mass and certain electrical contacts are touching. When these parts are in contact, an electrical circuit is closed. This is known as a state of closure. Two distinct formulations can be used to calculate the duration, or dwell, of this contact. In the first, this duration is determined based on purely geometric considerations. To be more specific, if the displacement of a sensing mass, in the form of a gold plated steel ball, relative to the tube in which it travels is of sufficient magnitude, the ball and contacts are assumed to be touching. However, because the motion of the contacts can be independent of the motion of the sensing mass, dwell should be determined based on a more exact theory. In this paper, the effect of separation between the sensing mass and the contacts on dwell time is studied through the use of an improved formulation. Closure is determined by investigating the sign of the normal force between the sensing mass and the contacts. Using this method, it is shown that multiple closures with very short dwell times, which may occur before a sustained closure, can occur in circumstances where the geometric model predicts a single closure with a significant time span. This phenomenon of short duration closures, known as tick closure, is extremely undesirable. Examples are presented to illustrate the ability of the improved method to predict tick closures which have previously gone undetected.