This paper describes our design of a simulation environment for electronic textiles (e-textiles) and our experiences with that environment. This simulation environment, based upon Ptolemy II, enables us to model a diverse range of areas related to the design of electronic textiles, including the physical environment they will be used in, the behavior of the sensors incorporated into the fabric, the on-fabric network, the power consumption of the system, and the execution of the application and system software. This paper focuses on two aspects of the system, modeling the motion of a person wearing the e-textile and modeling the effect of faults in the e-textile system. To partially validate this environment, we compare simulation results against results from two different physical prototypes, a large-scale acoustic beamformer and a pair of shape-sensing pants.