In this paper, an attempt is made to determine whether Cepstrum analysis can be applied to detect pure harmonic sine waveform acceleration-time signals in a frequency sub-band from the acceleration-time function of vehicle load platforms. Based on Cepstrum evaluation of specific measurement results at different speeds and under different road conditions, the analysis reveals that no frequency band exhibits full-period pure sinusoidal excitation, which casts doubt regarding usuage of sinusoidal sliding frequency tests for package shaking tests.