Found a capped off oval 8 receptical plug (although only 7 have a wire going into them) Behind the driverside headlight. It has 2 rows of four holes, the colors are: green/black red/black green/red black/orange purple/white purple/orange gray/white. It branches off from the main wiring harness that goes over the top of the radiator. I'm just wandering what it is for.

 

From what I can tell its listed as the "DRL" jumper location. Not 100% certain exactly what DRL stands for but every wire in that connector is linked in some way to the lighting/indicator lamp circuits in the truck. The red/black & green/black are the high beam/low beam power feeds respectively. The purple/white is the trigger/power for the brake warning lamp. The purple/orange is the power feed for the ABS relay,MLPS through to the backup lamps, ABS computer, cruise control servo/amplifier, HEGO sensor and trailer battery charge relay. (All of which would be capable of triggering indicators or lights of some sort) The gray/white is the hi beam indicator trigger/power. Finally, the black/orange is an unswitched power feed to the main light switch that feeds all of the rest of the lighting in the truck.

Thats an interesting discovery you've made there. In researching the wire colors and their significance I can see where testing to see if there is power at these circuits could be tested very easily by probing that connector at the appropriate pin and grounding the other lead of the meter/test light. Could save a lot of time checking things since you can access that connector right there and can even jump battery power to whichever pin necessary to "test energize" the circuit or circuits that you may have a problem with.

 

DRL: Daytime Running Lights

 

When i found it, it was mounted on top of the frontmost part of the driverside framerail. Maybe it was intended to be a test port for ford techs, or maybe for a auto headlights module that was never developed.