Did this on my old Ranger and couldn't find much on here about it so I figured I'd do a short write up about it....

Things you need:
Electrical Tape
Wire strippers
2x 1 or 2 foot sections of 16 or 18 gauge wire
Razor blade
Soldering Iron (optional but I recommend it)
Plastic Splice Connectors (optional)

After blacking out my headlights I noticed that from the side there really isn't much light coming from the turn signal/parking light that's reflected and can be seen from the side of the truck...


...and the mini side marker light doesn't flash with the turn signals. So using the info I found here Daniel Stern Lighting Consultancy and Supply I decided to include the side marker light as part of the turn signal lighting.

After removing the 3 bolts that hold the headlamp assembly in, pull the entire assembly out and remove the side marker light, disconnect the headlight connector, and remove the turn signal. Set the headlight assembly aside and you'll have something like this:


Peal back some of the electrical tape on both the side maker wiring and turn signal wiring. First, cut the black (ground) wire coming from the side marker bulb. Next you will want to take a razor blade and cut away some of the insulation around the +12 flasher wire going to the turn signal bulb. For the passenger side this wire is White/Blue and for the drivers side the wire is Green/White (2005 F-150).



For the passenger side: Take one of your 1 or 2 foot sections of wire and tie one end of it into the White/Blue wire and connect the other end to the black (ground) wire coming from the side marker bulb. The other end of this ground wire that goes back into the truck wiring harness can just be taped up with electrical tape. Next solder and tape or if you decide to use splice connectors do that and tape them up.



For the drivers side: Exactly the same as the passenger side except the wire you are tapping into is the Green/White wire coming from the turn signal bulb.

Now you are done... re-install the bulbs into the headlight assembly, reconnect the headlight, and use the 3 bolts to re-install the headlight assembly on the truck.

With the headlights and parking lights OFF this is what your turn signals or hazard lights will look like:
Picture008.mp4 video by backinblack98 - Photobucket

With the headlights or parking lights ON this is what your turn signals or hazard lights will look like:
Picture009.mp4 video by backinblack98 - Photobucket

(low quality video-actual flashing isn't inconsistent)

Enjoy your now safer and somewhat cooler turn signals!
Any questions just PM me.
Thanks

Eric