The # C59496 hardwire kit is a universal application, so I have linked the installation instructions below, but they are not going to be specific to your 2006 Mercury Montego.
To install the hardwire kit on your vehicle, you would use the included circuit tester to test the wires behind your vehicle tail lights for function. I would have a friend sit at the wheel and press the brake pedal or engage the turn signals as you test each wire behind your tail light. Once you have determined... view full answer...