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Old 04-20-2003, 09:12 PM   #1
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Need 7 pin wiring help.

I have a 2003 Dodge Ram that didn't come with the towing package. I installed the reciever and am attempting to wire the truck with a wiring harness that came from Dodge. There were no instructions for some reason. It has a 4 pin that goes into the 4 pin on the truck. That part is easy. There is a purple wire that I need to splice in (I guess) at the back of the truck. I assume that I need to splice into the purple wire, in the group of wires, going to the tail light. Is this for the trailer brakes? Or is it backup lights?? Next on to the front of the truck. There is a red wire that goes to the battery (I guess). It has a fuse in between the battery and the back of the truck. Also a blue wire that I think goes to the brake controller that I don't have yet. I am planning on splicing the purple wire, connecting the red wire to the battery and leaving the blue wire loose until I get a controller. Is that right? Will my trailer brakes work, but just without being able to activate with the controller?
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Old 04-21-2003, 04:59 AM   #2
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I am not to sure what the 2003 Dodge does for trailer wiring but here are a few tip that most new truck go by.
The "big" blue wire is for the trailer brakes there should be a blue under the dash and at the back of the truck. The red wire is it under the dash? if it is that goes to the controler. The fuse powers the red wire. Also the should be 2 more wires under the dash ground and a + trigger from the brake pedal. That should connect to the controler. Now back of the truck the 4 pin does all the lights. This is the colors white ground, brown running/marker lights, green is right blinker/brake light , and yellow is left blinker/tail light. You said that plugs in that done. The purple wire is the guess to me . Is it " thicker" then the rest? if it a thicker wire it use for a few options ex battery charging ,dome lights in a trailer or anything that need a contant 12 volts. Back up light are rare on most trailers. If you do have back up light you may have to run your own wires.
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Old 04-21-2003, 05:50 AM   #3
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1994 36' Classic 36
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Answer to the question

No, your trailer brakes will not work without a brake controller.

You can buy a four wire adapter for the lights but the reverse, charge line and 12 volts positive will have to be hardwired if you do not have the wiring harness that is optional equipment on the Dodge Ram. You can buy the wiring harness from any Dodge dealer. It does make it a little easier but the reverse wire has to be hardwired at the rear of the vehicle to the seven way connector.

No short cuts on this one.
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Old 04-21-2003, 01:27 PM   #4
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1996 28' Excella
Okemos , Michigan
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You are going to wish you got the factory trailer wiring. My 2003 Ram has it and hooking up was a dream. The seven blade connector at the bumper is completely wired, including reverse lamps and brake controller. You just have to buy a controller and plug it into a socket under the dash. (Hoppy) In your situation, I would not trust the wire colors for function. Run new wires from the brake controller to the battery and trailer connector. Lots of ty-wraps and a decent voltmeter. Good luck!
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