No trailer electrics

Hi, when I hitch up my trailer & plug in the electrics they do not work. The last time I used the trailer was around 6 months ago & everything was OK then, have tried the trailer plug on another car & all the lights & indicators work perfectly so the problem must be with my car. The old socket was damaged so I replaced it with a new one. I cleaned the wires before connecting up the new socket & made sure they were all correctly connected. All the fuses are OK too. I am prestty sure that the towbar & the 2 electric sockets are genuine Volvo ones. Does anyone know where the towbar sockets connect up to the main loom so I can check the connections there? I can see the 2 socket cables when I lift up the left side storage cover, they disappear behind the trim somewhere. It would save me removing every piece of trim until I find the connector if someone could point me in the right direction. My limited knowledge of electrics tells me it might be an earth somewhere seeing none of the trailer electrics work at all? Hope someone can help.

Trailer 

Hi just a thought , connect a wire from the cars earth to the trailers earth and with the socket connected see if the lights work? if yes its an earth fault if no its power ,at least it saves chasing your butt !! :-} Hope this helps Regards Mike B :mumbles: