Hello. Just joined so excuse any rookie mistakes or incorrect wording.
I have an '07 F350 King Ranch V10 with an electonic brake controller problem.
I haul bumper pull and gooseneck horse trailers with no problems until lately. My brake pedal is not engaging the trailer brakes even when I increase the gain. However if I use the manual control lever, the trailer brakes engage. This is the same for the plug at the bumper as well as the plug in the box. I checked fuses then pulled the wiring plug on the brake pedal and all appears fine. Any ideas? I'd rather not take it to the dealer without some prior knowledge of what it might be. Thanks

 

Under the hood there are some wires (somewhere.. I know where mine are for my 2002 but yours will be different) that connect the brake controller to the master cylinder, or something in that area. Perhaps something is loose.

Just a guess.

 

Couple questions - do you get any error messages in the dash? Do you still have the other trailers, or at least access to another? If it works correctly on the other trailers you can pretty much eliminate the truck as the problem.

Is this new trailer a horse trailer as well? Reason I ask is that the factory controllers sometimes don't work well w/ electric over hydraulic brakes, but those are usually only found on pretty heavy trailers...then again I've seen some pretty heavy horse trailers, but I don't know what kind of system those new trailers use. My horse trailers are all plain old electric brakes.

 

Thanks for the replies.

I'm checking under the hood for a bad connection to the master cylinder as well as I'm going to recheck the wiring harness under the dash.

I have seen "Trailer Fault" or "Trailer Disconnected" a couple of times.
This problem is happening with my own trailer (2 horse bumper pull) that I've had for 6 years and is also happening with a friends 10 year old 3 horse steel gooseneck. I've tried both the bumper and the truck bed options for plugging in both trailers.

 

Do the new integrated trailer brake controllers have a relay under the hood like my OBS truck? If it does, your relay could be burned up or the contacts in it could be going bad. You could try swapping a different relay and see if that fixes your problem.

 

Ok, if it's happening on 2 different trailers then you can probably eliminate them as the problem and you're back where you started.

Now to solve it...I'm not an expert on these, but it seems like if the trailer brakes get power when the slider is activated then your wiring should be ok. Hopefully someone will correct me if I'm wrong about that. You might take the rear plugs apart though and make sure there's no corrosion or anything. There was a problem w/ moisture getting in the connection on the earlier models and causing problems. You can also reach up under the dash and make sure the connection to the controller itself is well seated (if you have the drivers side "glove box" you can remove it by squeezing it together and letting it drop out and reach through that hole to see if the controller harness is well seated). Assuming all the wiring checks out, I think the next culprit could be the controller itself. I believe there's also a sensor on the master cylinder which senses how hard you push the pedal down and adjusts how much voltage to apply to the trailer brakes, the slider may bypass that sensor entirely so that could be an option as well. I can't help you about how to or if you can test it though. The dealer should be able to tell you for sure...but probably charge you $100 just for looking at it - I've seen the controllers on ebay for 150-$200. So you might be money ahead to just go ahead and try one, you can always sell it again if that doesn't fix it.

Or another (probably cheaper) option is to just unplug the factory controller and get an aftermarket one. I really like my factory one though, it's clean and works so much smoother being fully integrated into the trucks braking system.

Another thought - you mentioned you have a plug in the bed - you might trace those wires down and see where they hook into the main harness running to the back bumper. Ideally, this would have all been plug and play connections w/ a pigtail harness, but it's possible it was spliced into the wires of the main harness and there's now a problem w/ one of the connections there.

Sorry, I'm basically just spitballing here. Post back if you get it resolved though, I'd like to hear the solution.

 

Sometimes the controller just needs to be replaced.

 

You have already established the wiring is good and your connections are good with what you have already done. When everything works manually the problem is with the controller itself. The system which is activated via the pedal is at fault.

Steve

 

Damn helpful.........

 

Thanks all,
Was out all day so unable to post. Great advice. Thanks for the help. Will post my results shortly.

 

Whenever i have had that exact problem, it has been in the ground side of the plug. Either the trailer or the truck. I know you have tried 2 different trailers, but horse trailers are rarely used every day and will corrode the pins on the connectors as stated earlier. I worked on one locally for a lady from S. Carolina that had spider webs in it. Her trailer full of horses had pushed her all the way here. Get you a can of electrical contact cleaner and clean them really well and see if it does it. Spray it on the truck side connector too.

However, it could still be the controller as well.

 

If you have a bad ground why does the controller work manually, but not with the pedal? It is the same leads and contacts either way. All that changes from one to the other is the activating system (hand versus pedal).

Steve

 

Well, my truck will live to tow another trailer.
The fault was with the brake pressure transducer. Had it replaced and at the shop they hooked up to a trailer so I could test it. Seems to work just fine now. I'll test it again with my own trailer on Monday because Thursday I hook up to a loaded steel gooseneck trailer for the haul into the mountains.
Thanks for everyones interest and input. I'll definitely use this site again.

 

Glad you got it fixed - and thanks for coming back and posting the solution! Reps to you! It could help someone else down the line w/ the same problem. Let us know how it works after the trip, sounds like fun.