Circuit for adapting a receptacle socket in a towing vehicle for diverse trailer circuits

A circuit (26) for configuring a seven-terminal receptacle socket (10) in a towing vehicle to properly accommodate the particular one of several possible electric circuit configurations in a particular trailer that is being towed by the towing vehicle. The particular electric circuit configuration in the trailer - Figures 3, 4, 5, 6 are four possible configurations - depends on the particular lamps (52, 54, 56, 58, 72, 74) and brakes (50, 80) in the trailer.