Follow the taillight wiring harness, at some point, there will be a ground
wire going to a screw. Remove screw, clean terminal and metal it attaches
to. Replace screw with a stainless steel one, paint over to seal out
Good grounds are important, and sadly overlooked.
If the lights still don't work, find snap connectors, clean them, and try
again. If your still without lights, check for dirty / rusted sockets,
clean or replace as needed.
Still no lights, check fuse box, at the bottom there will be a pigtail for
lights, remove clean, try again.
Still no lights, with snap connector unplugged, run fused jumper to put
power to harness directly, fuse will blow when you probe ground. If any
other terminal blows fuse, you have a short. If all else fails, problem
may be in directional switch. Before getting too involved, try changing
flasher [ they almost never go bad ] Salted roads equal wiring problems on