Ca depend .... it depends on whether the light itself is bad, or whether it's something else, like a bad ground or wire. Test the light first by applying 12 volts directly to it, and if it lights up, check whether the wire carries 12 volts when it is supposed to and, if it does, check the ground.
In any case, I don't believe the entire 'chassis' where the light is fitted would have to be replaced.