losing voltage on lighting circuit

[KSever]

I have a 98 Club Car 48v that I'm trying get the factory lights to work on. This cart has the horn and lights but neither work when I got it. I have adopted this cart at work and when I got it the cart was sitting on it's side behind a pile of junk in the shop. So far I have replaced all the tires, batteries and am now attempting to get the lights to work. It does have a 16v to 12v reducer and I do get 12 volts at the light switch but as soon as I pull out the light switch I lose all the voltage at the light switch and no lights will work, if I take out the bulbs from all the sockets and pull out the light switch I do get 12 volts to the light sockets. I am stumped at the moment, any help would be appreciated.