Abstract: A testing switch is activated manually by the taxi driver or automatically at the end of a trip. When the testing switch is activated, a preselected plurality of pulses is applied to the computing means of the electronic taximeter. If the taximeter is in proper working order, the indicating means of the taximeter will successively and in unison display the numerals from 0 to 9 at the rate or about one per second. If the numerals do not appear in the proper sequence, or if the driver perceives that they appear at a rate markedly different from one per second, or if some or all do not appear whatsoever, he knows that the electronic taximeter is not in proper working order.