Need help wiring Trailer wiring harness

[K45]

For my montero it did not have the nice plug and go set up for wiring up the trailer hitch wiring. i have ran the wires to the appropriate tail lights, but I do not know which wire to tap into. I have the wire taps, so it is not going be hard, but I am not able to figure out which wire to tap. Can someone local help me to get this buttone dup? Thanks

 

[redneckjeep87]

Use a test light and prob the wires at the taillight

 

[shawn]

If you're going to tap into the taillights, the tow vehicle needs to use the same bulb for indicators AND brakes. If it has one bulb for indicators and a second bulb for brakes, you'll need an a-dapter kit with diodes.