Check the listing for details. Chevy Ram Ford Dual Function Signal Running Light Harness. Condition: New. Listed at 21.00 USD. Dual Function Signal Running Light Harness. If you want the turn signal of your truck mirror to function as a running light or a trailer side marker to function as turn signal , here is the adapter you will need. I will include a set for both mirrors / lights as well as a spare. Will have instructions for which wire to tap In where. You must follow instructions listed as they will not work the other ways Message me if any questions on how it is supposed to look and i will send you a video. Here are the Instructions; Black- To vehicle or trailer running light circuit Blue- To vehicle or trailer turn signal circuit Red- To vehicle mirror turn signal or trailer side light ***NOTE*** Some mirrors may require more wiring internally. These harnesses are generic and can be used across many different applications. For an explanation of how these lights operate you can go to the youtube link https://youtu.be/grgKFI9u94k