Automobile ignition systems with double-ended coils are classified under the group of distributorless ignition systems (DIS) family, used in the majority of contemporary vehicles. The characteristic feature of this type of system is the opposite (positive and negative) polarity of the central electrodes of spark plugs, being the load of the secondary winding of the double-ended ignition coil. The consequence of this is the difference in the peak value of the avalanche breakdown voltage of the gap between the spark plug electrodes - higher in the case of a positively polarized center electrode. The subject of this article is a technical solution that provides uniform polarity of the center electrodes of all spark plugs that constitute the load of the double-ended coil of the DIS. The polarity of the spark plug electrodes of all cylinders is particularly important in terms of measuring the leakage current of the insulator due to the aforementioned differential peak value at the gap between the electrodes. Uniform polarity of high voltage pulses also allows for conducting a series of comparative studies of the spark discharge energy on the plugs of individual engine cylinders. Such tests may be helpful in the case of attempts to identify the malfunctioning of the ignition coil secondary circuit, often leading to ignition misfire or increased fuel consumption.