you can do tachless, but sometimes you get problems when it does voltage sensing for the winter cold weather. you should be able to find it at an injector, the easiest one to get to is on the passenger side closest to the firewall. thats all assuming you have a 2000-2002 Lincoln LS. you can look at two of the injectors and this is what you can possibly see, ex. injector one black wire and blue wire, injector two black wire and green wire. you wont tap off the black wire because that is common between the injectors and doesnt have the RPM AC on it, so you grab the opposite wire color. I hope this helps.