Abstract: An apparatus for and method of testing the condition of a motor vehicle cranking system is disclosed in which the voltage at the battery terminal of the cranking motor is measured at one second intervals during cranking and compared to a set of predetermined minimum values stored in a computer lookup table according to the battery temperature and engine temperature during cranking. If a measured voltage is below a corresponding minimum voltage value, an indication is provided to the operator. The predetermined set of minimum values for each combination of measured battery and engine temperatures corresponds to the minimum voltages that would be provided at the measured temperatures by a cranking system capable of providing at least the minimum voltages down to and including the lowest design temperature.