year? what manual? the factory manual doesn't show any brown wire on the light circuits - brown should be the color for the gas gauge I believe - most years have a tab at the front of the switch that is one end of the coiled resistor wire and that runs the dash lights [that's the "dash terminal"], which get power thru the main supply to the switch - the "D" terminal on the switch is the Dome light, the dash light wires are all gray and usually they're all hooked together with a soldered or crimped joint, you probably didn't get the actual dash lights with the harness, but that "bundle" needs to get hooked to that rheostat on the front of the switch
Bill
