Transmission fluid change
More than likely, like most automatic transmissions, yours does not have an oil plug. You need to drop the transmission oil pan to drain the old oil... You need to buy a transmission filter/pan gasket kit. The filter is located on the bottom of the tranny. You will see it when you remove the pan. Replace the filter, thoroughly remove any traces of old gasket material, clean the mating surfaces, and reinstall the pan with the new gasket. Torque the pan bolts to the manufacturers spec (you should be able to get this where you buy the filter/gasket kit). Refill the transmission through the dipstick (Capacity for the Voyager is 4 quarts, make sure to use ATF Plus (Type 7176) for your particular tranny, NOT Dexron, Mercon, or generic automatic transmission fluid, Chrysler transmissions do not like any other kind and tend to fail quite quickly with the wrong fluid). Fill to the full cold level. Start the engine, move the shifter through all gear ranges, and put it back in park. Leave the engine running and refill to cold full. Drive the car for 5-10 minutes and, with the engine still running and the car in park, fill to Hot full. You should be ready to go!