Rear fog lights does not work

[Andyally]

Good afternoon. I have Toyota Avensis Wagon 2006 with Thule 3577 towing hitch. The problem is when I turn on rear fog lights, dashboard indicator lights up, relay is clicking, bulbs are ok, however fog lights don't work. I have towing hitch which is connected to tail lightning wiring and it works in the way, that when hitch is connected into the socket, fog lights are disabled. I heard that problem can be with oxidation of connectors and wiring inside the socket, but I can not open it because bolts are so rusty, so I am wondering is there any electrical hitch wiring scheme online to refer to?

[FROSTYBALLS]

Moved to the Avensis club.