I had Dodge install the hitch and 7-pin wiring (big mistake) when I bought my 05 3500 dually. I hooked up to my trailer for the first time yesterday and no electric brakes. I traced the wiring back to the engine compartment and found a blue wire that was not connected. They didn't give me the wiring instructions so I have no idea where it hooks up to and I would rather not let them touch my truck. If anyone has a diagram they could post or email me I would be greatful.

TAI,
-Allen

 

Try this.
http://www.klenger.net/dodge/7-pin-c...tow-wiring.pdf

 

The blue wire is usually the electric brake wire that hooks up to your electric brake controller inside of the cab. They probrably just ran it to the engine compartment and left it for you to feed into the cab.

 

In order for the brake controller pig tail to work, the blue wire has to be run to the connector under the dash above the emergency brake. Seems to me if they left it loose, you need to take it back to the same dealer and get them to finish the job. Just my $.02.
Nat

 

You say that blue wire terminates in the engine compartment.

Where does it originate? If it comes from the harness under your dash that plugs into your brake controller then you need to pull the wire back into the cab and then run it back to the 7-pin connector at your back bumper. Like what has been already said, the blue wire is the output from your brake controller to actuate the trailer brakes.....assuming they wired it standard.

Once you get the blue wire to the back, the standard pin for trailer brakes in pin #2. Try this page for reference:

http://www.etrailer.com/faq/wiring.asp

I live in Grapevine. PM me if you need any help.
Tim

 

If you remove your driver side inner wheel well liner, you'll see a large grey connector. All wiring on all the Dodge Ram's (regardless of whether they were ordered with the tow package or not) are exactly the same, including the interior wiring) up to that point. From that connector, the non-tow package equipped Rams are just missing the blue brake control wire and the 12v trailer supply wire. When you look at the connectors, you'll see that the connector closest to the engine has two extra wires going into it and the other has two less wires coming out of it as it continues toward the rear of the truck. The blue wire will tap into one of those two wires. I can't remember what color it is, though. Easiest way would be to have someone press the brake pedal and use a 12v test light to poke the wire. Of course, it should light when the brake is pressed and not light when the brake's not pressed. The 12v supply wire will always light. If you need any further assistance, let me know. I've got the service manual on CD and will look it up or email you the necessary pages. I know all this because I had to do the same thing to my truck. The dealer messed up on the order and forgot to add the tow package to it. Rather than taking it to the dealer and letting them do it, I did it myself to try to achieve the factory-like installation, therefore I ran both brake and power wires to that connector and tapped them in there. I wish I could've installed the wires into the connector itself, then it would've been exactly like the factory.

 

Thanks for the great responses everyone.

jlasich, that is exactly what I was looking for. My truck also came in with out the factory trailer harness and Dodge installed everything for free, they just didn't finish the install.

-Allen