I have a 2006 F150 with the standard 4-pin trailer plug on the rear. I would like to swap it out for the 7-pin using the OEM harness. Can anyone please tell me exactly what I need to do this? I need to have trailer brakes and also a battery charge circuit for the trailer. Is it true the trailer brake wire is already installed and just needs to be hooked up?

 

You should only need to change the wiring from the connector by the spare tire, and install the relay and fuses for this.

Take a look at the sticky at the top of the towing and hauling forum, few members did the same thing you are trying to do already ( mind the part numbers, there are 99-03 and 04+ part numbers and diagrams in this thread )

https://www.f150online.com/forums/sh...d.php?t=184757

 

So, is the brake connector that is up under the dash by your right knee on all trucks? Mine is a '06 F150 without the tow package.

 

That one sounds like the ABS diagnostic connector ( left knee by brake pedal release / hood release area ? )

Look for another one, that is by the right knee, 6 pins ( 2 rows of 3 ), by the ODB-II connector.

This is from the trailer tow install that comes with the tow kit.



Drop me an email via my profile, and I can send you the trailer tow install directions scanned into a PDF.
Note the MY of your truck in the email, so I don't grab the wrong one.
Lord knows, I'll get the email, and in haste forget to look back here for your MY in your profile and send the wrong series ( 99-03 version or 04+ version ).

 

SCULLY, I sent you an email.

Now, if I put the 7-pin factory harness in at the rear will it already have connected the trailer charge line and will I just have to install the relay(s) and fuses??? OR, will I also have to find that wire at the rear of my truck?