An apparatus for testing switches of a vehicle audio system includes contact bars. In use, a front end of each contact bar contacts either one of the switches, or a portion of the surface of the audio system. A front end of an extension bar is connected to a rear end of each contact bar. A gear unit is connected to a rear end of each extension bar, to move the extension bar forward and rearward. A motor is mounted to each gear unit, to rotate the extension bars. A piezoelectric sensor is mounted to each motor, to measure the pressure applied to the contact bars. A control unit compares the pressures measured by the piezoelectric sensors with set values, and diagnoses the switches.