The 7 way connector on the Berkshire, being factory Freightliner, will have as output for left turn signal, right turn signal, park lamp, and ground for the towed vehicle or trailer. The other pins should be for 12 volts, electric brakes, and reverse lamps. The turn signal outputs, when constantly on, are used as brake lamps. The connector on the coach should be wired in a universal manner so any trailed vehicle can just be plugged in. Just remember, the way the electrical system is configured, that if the coach lighting is working correctly, it doesn't mean that there couldn't be a fuse open for the towed vehicle and the toad's lights won't work. Checking the toad's lamp operation occasionally is recommended. Tell your installer that you already have the coach wired for trailer with a 7 way connector.