I have taken out any problem with the truck by creating a “truck like” plug that I connect to a spare battery so all of the wires have positive, except for the white that is a ground.The ground seems to be fine up until the tongue hinge. With no lights working, if I take a jumper wire and touch it to bare metal on the one side of the hinge, and touch it to a bare spot on the other side, the lights come on.Its like the pins and the hinge sometimes make a connection, and other times it doesnt. A wire across seems to be the fix.