Hello, all. I just purchased a 2005 Supercrew. This truck did not come with the towing package. It did however come with a 4 pin plug mounted under the bumper - I guess if anyone wanted to use the bumper for towing. Can I change this plug to a 7 round without having to run any extra wires? Is there a plug under the centre console for a brake controller? The owners manual indicates fuse locations for the electric brakes and for the 12V accessory wire. Has anyone had any experience with these. I'd really appreciate any input on this topic.
Thanks,
Paul.

 

There are the appropiate wires under the rear to compete the 7 pin connection. All F-series trucks since 1997 come equipped with a standard wiring harness to fullfill all truck factory options.

If you follow the 4-pin trailer plug back you will find the connection where you can upgrade to the 7 pin. A lot of people will go to Ford for the new 7-pin harness that plugs right into the connection at that location.

As far as the electic trailer brakes, there is a grey 6 pin connector under the dash above the OBDII port on the drivers side bottom end of the dash above the accelerator pedal. You will need a Ford specific wiring harness and a brake controller to compelete the install.

 

I just installed a 7 and 4 pin connector combo, plugged right in to where the 4 pin did up on the frame (driver's side) as Colorado mentioned. It's handy having both and are available from Ford dealer.

 

If it didn't come with the towing package, you will also need a couple relays.

 

Ya, like he said^, just check under hood versus in your owners manual's diagram, you should be missing 2, a larger one and smaller like the sticky at the top of these threads shows. Good luck, can't wait to try mine out myself.

 

Thanks for all your info guys. I got everything installed. Everything seems to work with the exception of the 12v accessory pin. Would this have to do with the "relays". I havn't checked to see if they have been installed. Anyone know what the purpose of these relays are?
Paul,
'05 Supercrew.

 

The relays are for your electric trailer brakes and aux charge line.

The purpose of the relays is to seperate your truck wiring integrity from the trailer. The truck powers the relay, and the relay gets it power from a different source to go to the trailer.

A main reason for doing this was some trailers have huge pulls in amps for things like running lights when there are a lot of light installed. I have seen trailers with over 100 running lights. By relaying the power to the running lights it takes the strain off your headlight switch preventing melting or burning up of the tow vehicle wiring/switch.

Some trailers run large accessories requiring a large amp draw off the aux charge line instead of running the aux line to a on-trailer battery.

I hope this makes sense?.

 

Perfect sense - thank-you. I never thought of the additional load on the switches. I thought that because they were separately fused and a heavier gauge wire that a relay wasn't necessary. Good thing I never had a problem with my last vehicle. (No relays installed)
Thanks again, now I just have to find these relays. Are they Ford specific? Or can I get them from a parts place?

 

Interesting... my truck came with the factory tow option, but didn't include the 7 pin adapter. (Then again, they made my truck with totally weird options... and stuff that shouldn't have been on there.) I traced the wire all the way back, and yep, all I need is the factory 7 pin adapter.

Now about those relays... anyone know?

 

Just been through it and everything works perfectly. Thanks guys for all of your info. By the way I was only short the one relay. I also had a 4 pin on mine. Trace those wires back to the main harness and you will find two wires on the primary harness which are not continuous with the secondary harness.(They are easy to find because they are thicker) One is blue and the other is orange. The blue is wired to the harness located just under the steering wheel if you would like to plug in an optional brake controller. The orange wire is 12 volts (Tow Charge) which will only work if you get the relay for the internal fuse/relay panel located in the passenger footwell. Hope this helps you. The extra 3 wires in the seven are:
1. Brake controller
2. Tow Charge
3. Reverse lights.