Park lights and side marker lights

Find the fuse for the lights by unplugging them one at a time and watching for when the lights go out. When they do plug it back in and see if they come back on. If they do you've probably got some wires that are shorted to ground possibly through one of the light sockets. Take all the lights that are on and take the bulbs out one at a time like you would Christmas tree lights. Take note of the condition of the sockets. Are the bulbs stuck in ther from corrosion or doe anything look overheated or burned. Also follow as much of the light switch wires as you can see to check for cracks or frays. Do the same with the socket wires