Classic/Antique Car Repair: 72 mustang, test light, wiper switch

Question
I am installing a new universal washer bottle to my mustang and I was wonder which wires to connect the washers wires to on the back of the wiper/washer switch on the dashboard?

Answer
Did this car not have washers installed in it before? If so the wire should be right there in the engine compartment for the washer. On the after market system that you are using one wire, if it has two wires, one goes to ground and the other back to the switch. To locate the wire on the switch, ground one end of your test light and probe the contacts on the switch with the washers activated. Make sure that the ignition switch is in the on position and that the connector is on the wiper switch. You might have to probe the wires with the test light. The only one that lights the test light is the right one. Make sure that the one that you have picked does not light up the light when just the wipers are turned on. If so keep checking. If you don't have a test light they are available in any auto parts section and they don't cost much.