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Discussion Starter · #1 ·
Ok, I've got a 2011 Duramax that came equipped with the factory trailer brake controller. I've put an M&W goosneck hitch in the truck and I've used it a few times pulling a flatbed around. My problem has been that when I hook up and plug it in, all the lights work fine, but the trailer brakes won't release. I use the factory installed wiring connector on the back bumper with an adapter to hook it to a 6 pin round wiring harness that is on the trailer. I don't know if that has anything to do with it or not, but we use the same adapter to hook it to the factory wiring on my uncle's Dodge and it works just fine. I've also hooked my truck to a couple of other trailers to test it and I find the same results.

Once it is hooked up, I play with the trailer brake output, but it just never will let the brakes release. I've checked fuses and everything and it all looks fine. So at the end of the day, I end up pulling the trailer around on backroads from one farm to another anyway, so I just unplug the wiring harness, the trailer brakes release and I let it roll freely.

Today, I decided I should really look into it and figure out how to get the brakes to work. I looked back through the manual, and if I read it right, I thought it said that even if you have the factory installed brake controls, they don't hook up the wires to the controller. It basically said that the wires and fuses will all be in place, but they aren't connected to the fusebox and the controller in the dash. This seems absolutely ridiculous and wrong to me, and I couldn't tell if that meant maybe just for a truck that didn't have all the factory wiring provisions hooked up or something. Has anyone had any experience with this? Is it true? I actually called the service department at the local dealership to ask about that and he couldn't answer my question.
 

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I ran into this on an 02' some years back. I'm assuming the same 7 blade to 6 pin adapter. Inside the adapter all the wires are soldiered except for the charge wire and brake wire. By switching those two wires inside the adapter the problem was cured.

I know with it working on your Uncle's truck and the same adapter you would think something else was wrong. Are you sure the trailer brakes were really working on the dodge and that the charge fuse was not blown?

When testing your truck on different trailers were you using the adapter?

For something so simple there could be a few thigns going on. I have even had a bad ground backfeed running lights through the brake coils and cause them to come on. If you don't feel like switching the wires, try pulling the charge fuse and see if the brakes release.
 

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sounds like brake wire and 12v source are swapped. remove fuse for 12v trailer power and see if brakes still lock.
 

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I had the same issue with a horse trailer with a 6 pole plug. The charge and brake wire were reversed. I just switched them and all was good. These new trucks come with all brake and charge wires hooked up and fused - ready to go. Good Luck.
 

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Discussion Starter · #6 ·
Yes, the trailer is electric over hydraulic.

The main thing I was trying to figure out was what the manual was trying to say about wiring not being hooked up.

When I've hooked to other trailers, I've used an adapter, but not always the same one that is on the flatbed for my uncle's Dodge. I've just NEVER had the brakes work on any trailer with this truck, so I was just trying to figure out what's going on.

As far as the comments about trailer wires being swapped... I'll check on that. If I find anything there, I'm not sure I've got a good way to fix that though, seeing as how we've got about 3 or 4 trailers that could get swapped between about 5 different trucks (2 Dodges, 3 Chevrolets) and right now, my 2011 is the only one that the brakes don't work with. Not saying that something isn't backwards on all of the other trucks, but they weren't all wired by the same person so it would be a heck of a coincidence.

Thanks for all the feedback.
 

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The factory brake controller on the new Chevy/GMC will not work on electric over hydraulic without a special device on the trailer. All it is is a magnet(resistants) in series with the brake actuator on the trailer. My 5th wheel trailer has hydraulic brakes. When I got my 2011 GMC Sierra I had to add this device to fool the brake controller that I had electric brakes. etrailer.com sells them depending on which kind of brake actuator you have on the trailer. Contact the trailer manufacture to see what kind of brake actuator you have. They may even supply the right device. Ford and Dodge don't need this device.

Walt
 

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Does the 7 to 6 adapter stay with your truck and the other trucks have their own or does the 7 to 6 adapter stay with the trailer? It's common for a 7 to 6 adapter to have the center pin and side pin reversable, since many people wire the 6 way different. That would explain why it only does it on your truck, becasue it's the adapter that needs changing and not the truck or trailer.

Like JDWLT said, the factory controller isn't compatible with the electric over hydraulic brakes, but that's not causing your brakes to lock up. The modules are expensive, so what I normally do, is wire in a resistor. On the trailer, take one side of the resistor and hook it to a ground and tap the other side into the blue wire leading to the brake actuator. These are the ones I use Putco LED Light Bulb Load-Resistor Kit - Aluminum Putco Accessories and Parts P230004A or some people just wire in a magnet, but this is smaller and cleaner.
 

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Discussion Starter · #9 ·
I've been reading some other information on it this morning. I'm thinking about just putting in an aftermarket brake controller in my truck. Quite frankly, most of the towing I'm going to be doing will be hauling a backhoe around with this one flat bed, but it is possible that I could need to hook onto another trailer and I'm not too crazy about the idea that I'm going to have to make modifications to any trailer I might hook onto with electric over hydraulic brakes. I think it is just ridiculous that they make an integrated controller that won't work with them.

As for the questions about the adapter... Yes, there is one that stays with the trailer all the time, but I also have one that is mine that I keep in the toolbox on my truck. I've used both with the same results.
 

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Yeah, it's pretty stupid that they're not compatible, I don't know what GM was thinking. I got to thinking, the electric over hydraulic actuators run of the 12v trailer charge wire (the charge wire takes the load) and just uses the brake control wire as a signal to engage. So, if the brakes were coming on, it must of been engaging off the pulsing signal of the factory controller. Could you hear the actuator running or pulsing?

I agree that you should just go aftermarket, you should probably just put a P2 or p3 in it, so you can tow whatever you want.
 

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all you have to do guys is put an electric brake magnet on the break terminal and ground on the trailer, (i had enough room in my terminal box) thats it 20$ and thats it, did it with mine works awesome, no need fore new break controller...
 

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Discussion Starter · #12 ·
all you have to do guys is put an electric brake magnet on the break terminal and ground on the trailer, (i had enough room in my terminal box) thats it 20$ and thats it, did it with mine works awesome, no need fore new break controller...
I get where you're coming from, and I don't disagree with what you're saying. If I knew I was only ever going to pull one trailer, I'd definitely go that route. The thing is, if my sister wants to borrow my truck to pull her horse trailer, or my buddy wants me to pull his camper when we go camping this summer, I don't want to have to worry about whether we're going to have to screw around getting the brakes to work. That's why I'll probably look at putting in a P3. It isn't going to be too expensive to buy and install one and then I just don't have to worry about it.

Really, if the integrated controller isn't going to work with certain types of brakes, to me, it is worthless. Just my opinion though...

Thanks to everyone for the feedback.:thumb
 

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I get where you're coming from, and I don't disagree with what you're saying. If I knew I was only ever going to pull one trailer, I'd definitely go that route. The thing is, if my sister wants to borrow my truck to pull her horse trailer, or my buddy wants me to pull his camper when we go camping this summer, I don't want to have to worry about whether we're going to have to screw around getting the brakes to work. That's why I'll probably look at putting in a P3. It isn't going to be too expensive to buy and install one and then I just don't have to worry about it.

Really, if the integrated controller isn't going to work with certain types of brakes, to me, it is worthless. Just my opinion though...

Thanks to everyone for the feedback.:thumb


just saying out of all of those trailers you named i only see one that might have elec/hyd brakes, which you very rarely see in most case's cause its so damn expensive to do/option.

secondly, if you are that worried about it, make an extension/pig tail to plug in between your factory 7 way and your trailer connector, integrate the magnet/whatever youd like to use to draw enough power for the truck to recognize it. literally $30-50 and you are done, easy as shit but again chances are you will very rarely have the issue of elec/hyd brakes
 

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Discussion Starter · #14 ·
secondly, if you are that worried about it, make an extension/pig tail to plug in between your factory 7 way and your trailer connector
Hmm... hadn't thought about that one. I might give that a try. Thanks. :thumb
 

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Hmm... hadn't thought about that one. I might give that a try. Thanks. :thumb
i think outside the box on alot of things, the way i look at it is; its cleaner less hassel and i like the heads up display of the factory break controller,, and shit thats easy and cheaper then a 175+p3 lol


(i do like the p3 have it on my semi)
 
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