usually when they do this one of the bulbs is bad on it,take them out and look at all of them and make sure they are all making good contact with the socket they fit in to,you may have to try changing them to get them to work right ,i used to own a trooper ,pretty good vehicle,mine did what yours is doing after i put a trailer hitch on it and wired it up,i had to change the flasher to a slower flashing one,,good luck.