Lights
The ground for the cornering lamps is the base of the bulb holder, this is pressed into the cornering light housing which is die cast. Turn the light on and run a wire from the bulb holder to a know ground. If it lights it is a ground problem. I have seen corrosion here from a bad lens seal and the bulb holder corrodes in the die cast, I have just soldered a ground wire to the bulb base and then to a know good ground. Could also be a bad turn signal switch but check the cornering light on with a test light first if it lights it is a bad ground.