IPC(industrial personnel computer) emits the frequency signal to simulate the rotating speed through timer 8253. However, ECU(electronic control unit) sometimes can not recognize the discontinuous frequency signal. Lifting wavelet is widely applied to locate the abrupt signal because it can simultaneously show the local characteristic of time domain signal and frequency domain signal. Fourier transform and lifting wavelet are used to detect the rotating speed change, respectively. The simulation results show that lifting wavelet can accurately and effectively detect the singularity of vehicle speed change such as speed decreasing and speed increasing, but Fourier transform fails to detect these singularities. Accurate singularity acquisition by lifting wavelet has potential application for further improving ECU performance.