I have a 2008 f-250 with the integrated brake controller and when i hook it up to my trailer it wont come on. When i manually slide the slider to activate the brakes it activates the brakes on the trailer. I checked the wiring all the way back to the brakes and everything is good so im not sure whats up with it. Just weird how if i manually engage the brakes it says "trailer disconnected" but still activates the brakes. Any ideas?

 

First guess - poor ground in trailer. Check the ground pin in the trailer side connector (plug) to be sure it's really grounded to the trailer frame and making good connection to the pin in the truck socket..

 

I actually just put a new plug on th trailer wire and sprayed out my plug on the bumper with contact cleaner. the lights and everything work like a champ its just the brakes that dont activate the controller.

Ive been thinking its the ground too because i was pulling my 5er the other day and it came on for a few minutes and worked just fine. then it started blinking off an on. this is starting to get old....

 

are you sure the brakes are connected to the correct pin on the trailer side?

...are you sure that your manual slider is actually braking the trailer? What you described will happen even if no trailer is connected.

 

Mine does the same thing. One of my trailers it shows everything is fine(newer trailer) on another it shows disconnected but they work. I have had it in show 3 times to figure it out and no luck. New magnets, new plug, and wiring confirmed. It does this on both of my trucks with factory controllers, but if I hook it to my 150 with a P3 controller it works fine. I think it is just an issues with some of the brake systems on some older trailers. I don't worry about it because they do work even when it shows disconnected. Just my .02

 

Yes im absolutely sure its connected correctly. And how do i know its braking you ask? Well, when i slide the slider it stops the truck. duh! The controller just isnt coming on when the trailer is hooked up.

 

I hope you are not depending on the trailer being hooked to the truck thru the hitch as your ground! This is the most common problem. Unhitch the trailer from the truck, then see if you still have running lights on the trailer.

If no, you need to run a heavy gage ground wire thru the 7-way plugs. Or check the electrical plugs for rust/bad ground. Esp on the truck... water seems to corrode the wiring on the truck end INSIDE the connector.

 

Some older trailers have substandard wiring. The gauge of the wire is too small causing the controller to think there is a poor or no connection. The no-frills controllers will work on these trailers, but the high end ones with diagnostic capabilities go stupid.

 

Seriously, it is usually the ground connection at the trailer frame. Check it and clean it, then reattach and coat with some grease or Vaseline.

 

Same thing is happening on my truck, '08 F-250. What I have read on this issue is that water will get into the back of the 7 pin connector on the truck side. You can remove the harness from the bracket (that the trailer plug mates to) and inspect for water / corrosion. Unfortunatley I haven't been home to try this out and see if it works myself, but it's one of the first things I'm doing before hooking on the the trailer. If it's happening on two trailers, I'd say it's the truck. From what I've read, and what others have said here, is that these TBC systems are very picky to corrosion and other wire issues.

Best of luck and let us know, there are plenty more with this problem.

 

Did you ever try an "ohm the brake leads on the two trailers and compare resistance. I'm just curious as it seems like this must be a connection issue somewhere.

Steve