visual warning light


can someone point me in the direction of the wiring for the visual warning light while towing saw in old posts using search that there is 2 wires coming out of relay to connect a bulb to but i cant find them found 2 wires but different colour to what was said,conected up tester to them while trailer indicators were on but nothing thought it to i have to dismantle dash have been upside down in footwell but cant see nothing,tried connecting audible box to plug wiring but not working. any help much apreciated.