2004 Mercury optimax 225hp trim gauge

My boat has analoge gauges. I have changed leg and it has a 3 wire digital trim sender. I have a short harness plugged into engine loom and other end is blank. Hanging out of this I have the 3wires to connect to my new sender. There is multiple Brown/white wires(male & female plugs)which one will make the analoge gauge work? I have tried the wire that is closest but no luck