trailer brakes

[RK55guy]

i am having issues with my trailer brakes and or control box. my truck was factory wired for trailer brakes with a plug under the dash. i bought a hopkins control box and the adapter harness to connect the box to factory plug under the dash. as soon as i hook the plug the control box in my brake lights on my truck come on and when i plug the trailer up the brakes engage. makes me feel like the plug and play adapter harness may be wired wrong. any info will be appreciated.

 

[aczlan]

What year and model truck? What model number Hopkins box?
I know that when we put a brake controller in our 2005 GMC half ton there was a pin that was left out which you had to put in a different hole depending on what year it was.

Aaron Z

 

[RK55guy]

its a 2001 dodge 2500 cummins. the controller is 47235 and the adapter is a 47755

 

[AllDodge]

its a 2001 dodge 2500 cummins. the controller is 47235 and the adapter is a 47755

Shows the correct items, what trailer connector is on the truck (6 or 7 round)?

 

[RK55guy]

i am not sure if its a 6 or 7. how do i tell which one it is.

 

[Birdhunter1]

The trailer side of a 6 round will be like a 1” or 1 1/4” size plug and have 6 round holes where a 7 pin will have 6 slots running (roughly) parallel to the outer edge of the plot as well as a receptacle to go over a stud in the center of the plug on the truck, the whole contraption will be closer to 2” diameter.

 

[RK55guy]

ok, i will post what i have tomorrow. electrical stuff drives me crazy. thanks for yalls help.

 

[RK55guy]

going by birdhunter1’s description, i have the 7 pin on my truck and it appears that the plug from the trailer should match up when plugged in.

 

[thekkfan]

Is the 12v pin in the harness at the brake controller have 12v all the time, or only when you hit the brake pedal?

If only when you hit the brake pedal the 12v and brake wires are crossed either in the harness or miswired in the truck. That would explain why you have 12v all the time on the brake wire.

 

[LouNY]

there are so many different wiring diagrams and trailer connectors, between round pin and flat, 6 or 7 .
if you goggle trailer connector pin outs you can find all the different ones and the color codes.

 

[Fallon]

there are so many different wiring diagrams and trailer connectors, between round pin and flat, 6 or 7 .
if you goggle trailer connector pin outs you can find all the different ones and the color codes.

Trailer Wiring Diagrams | etrailer.com

Of course that assumes things are properly wired with standard color codes. Trailers are often wired with non-standard colors, especially older ones. Not sure if truck manufacturers color code the OEM plug wiring or not.

The gold standard is always testing it yourself. Either with a multimeter, test light or fancy $10-20 plug tester (which is just a handful of test lights on a plug). The Etrailer page lists out what pins do what if you scroll down.

 

[thekkfan]

Got nothing to do with the trailer plug.

He stated his brake lights were on the truck soon as he connected the brake controller. Then the brakes automatically locked on trailer once he connected it up. Tells me the trailer is correct.

 

[Fallon]

Got nothing to do with the trailer plug.

He stated his brake lights were on the truck soon as he connected the brake controller. Then the brakes automatically locked on trailer once he connected it up. Tells me the trailer is correct.

Possible. It depends if the trailer was plugged in when he connected the controller. The wiring fault could be in the trailer. I'd consider a trailer more likely to have issues than a truck. But if the trailer isnt connected & things are going wonky, ya, definitely an issue with the truck or brake controller.

 

[TractorGuy]

Not sure if it makes a difference or if it's different on a Dodge but my F150 required the installation of a relay in addition to the harness and adapter. My truck came from the factory trailer brake controller ready but I had to supply the controller. The tow package had the adapter harness and the relay in a bag in the glove compartment. My Tekonsha Prodigy controller plugged right in and worked perfectly.

You problem sounds more like something is wired incorrectly though. See if you can find a different trailer to plug it into for comparison. That would tell you if it's on the truck or trailer side.

 

[rocketfish]

Check all your grounds. They can make a lot of things go wonky! It has happened to me more than once.

 

[AllDodge]

You have something miswired and can be the trailer of the truck. Looking at the parts obtained and installed in the truck, my first thought is there is something with the trailer. The link posted by Fallon in post 11 would be the one to check out. The trailer may be back feeding the lights and brakes

 

[RK55guy]

not saying the trailer isnt the problem but it is a brand new homesteader brand trailer. i called hopkins support and he said it could be the control box. now, as rocketfish said, im wondering if it might be that the ground is not good enough for the brakes. ive read that brakes require a real good ground but all of the lights on the trailer work. anyway i appreciate all of yall trying to help me get this fixed

 

[RK55guy]

finally got my trailer brakes fixed, called hopkins customer support and he had me do some tests and determined that the controller box was faulty. took it back to autozone and they exchanged it. hooked it up and now everything is golden. again thanks to all of for helping me

 

[aczlan]

Glad to hear that it's working. That makes sense as to why it was misbehaving the way it was.

Aaron Z