when lightboard is hooked to trailer fog lights come on?

when i plug my lights in to the jeep,the fog light on trailer and car comes on and wont switch off(only if the headlights are put on)and nothing else works.If the lights are not on everything works as it should..is this a problem with the car socket or the wiring on the car itself?I have recently replaced the car socket with a new one but it had a fog light cut off facility on it..where as the one before was just an ordinary 7 pin...i have spoken to someone that has said that the new plug should still have worked but i am not so sure..this morning when i tried again it fused all the lights out on the car..help please.