Hello all,
I have a question for the wiring experts. I have an 07 F150 FX4 with the 7-Pin OEM factory trailer tow connector. From what I can tell, it appears to have all the wiring I need for wiring up the interior lighting and the Third Brake light that will be coming with my new SnugTop XV camper shell I'm ordering soon. The 7-Pin trailer tow connector appears to have a backup/reverse wire connection, a 12 Volt connection, and a electrical brake connection that should work for the third brake light. I do know that there is also a CHMSL (Center High Mounted Stop Lamp - fancy acronym for third brake light) light-green wire (not connected to anything) somewhere in the rear of the truck wire harness for the third brake light too, but if I can get everything from the 7-Pin trailer tow, that will be much easier. I don't use the 7-Pin trailer tow connector for anything, and could make a plug for wiring the SnugTop to it, and still be able to remove the plug if I ever do tow anything with the 7-Pin. Does anyone know if this will work? According to this link: http://www.marksrv.com/wiring.htm, all the wiring appears to be 14 gauge or thicker. And does anyone know if the Pin 4 Black wire 10 Gauge Battery + wire, which I was thinking to use for the interior dome lamps of the SnugTop XV, is constant hot at all times, or just when the truck is keyed on?

I want to know all this because the wiring done by the Gem Top dealer 10 years ago on my last purchased camper shell was strung poorly.

Thanks in Advance,
JSB

 

The battery + wire is hot only with the key on. You are not going to be able to use the brake light wires from the trailer plug for your highmount third brakelight. It will blink when you turn the signals on. You may be able to buy a adapter box that will take both left and right brake/turn wires, and convert it to a third brakelight function.

 

Thank You, Franklin2, for that info. I took a look at the wiring schematic from the 2007 November edition of the Ford Workshop Manual and Wiring Diagram DVD, and you are right, the Battery + will only be hot with the key on. As for the electric brakes pin/wire, just to satisfy my curiosity, it would blink for a third brake light because the electric brake pin/wire on the 7-Pin factory trailer tow connector is electrically pulsed for pulsing the intended electric brakes? (PS. I don't have an electric brake controller in the cab, so maybe that wire won't be connected to anything hot anyway?)
Thanks,
JSB

 

Should be easy enough to test with a test light or multi-meter!

 

Yes, if you do not have a brake controller, you will not get anything on the brake wire anyway. And if you did have a controller, the voltage slowly rises based on time or braking force(depending on the controller), so the light would do some weird things.

 

Thank You.
JSB

 

I cant remember who makes it but their are converters out their for the brake lights check with a place that sells camper shells, as far as the hot wire you can locate the relay under the hood cut the small power wire that comes on with the key grab a constant hot under the dash somewhere run it through a switch & run it out to the relay hooking it on the wire you cut. I did this on our work truck to run a salt spreader off the 7 pin.