Hi welcome to the forum.
You will only get power at pins when that particular function is operating, so for example road light circuits will only be live if the road lights are turned on, on the car.
Power for charging battery or the fridge will only be active when the engine is running. I could be corrosion on the connector.
If that has been the case and you are still getting nothing, then there is a problem somewhere in the cars circuitry.
Unless you are competent with electrics I suggest you get it checked and repaired by a professional