The 2 larger (grey, green)plugs connect to the back of the cig lighter panel to nothing. the other (red)was hanging behind the panel. there is also a single wire purple with white stripe connected to nothing. Can you help?

 

Im not positive but i think the one left of the cig lighter plug is for the back up sensors

 

^x2 I'm almost certain you are correct. I haven't opened up my dash in a while, but if I remember correctly you are right.

 

backup sensors and in some cases, the 4x4 option. Depending on your model, your main wiring harness would be the same for models that had the possible 4x4 option.

 

its for traction control if you have it

 

The 2 plugs connected to nothing on your lighter panel are for T/C and reverse sensor system which your truck did not come with oviously...the third plug may be for you stereo system for sub out that you don't have either...that's a guess...good luck