In order to verify detailed impedance and wakefield simulations, the resonant modes in an aluminium model of the 9-cell ILC crab cavity were investigated using a stretched-wire frequency domain measurement, as well as bead-pull measurements. These measurements were compared to numerical simulations in order to be confident that all possible high impedance modes have been taken into account. The analysis of the results and the accuracy and limitations of each method is presented. It is found that measurements of all of the measured higher impedance modes have R/Q values whithin an order of magnitude of the calculated values. No mode was detected with the measurements that had not been predicted using simulations.