the wiring to your
lights should enter under the road side bench at the front, there are usually joints there, its a common place for a bad ground connection(usually a bunch of white wires under a crimp connector.)
From there wiring generally runs along the road side to the back where it meets the roadside tailight,(more joints) then across the back to the curbside taillight(more joints)
You may have to carefully peel back ensolite below the benches to access the connections.
Joe