Factory Brake controller
 

On my 08 F350 the factory controller does not seem to be working right. when I connect the trailer the brakes do not work right. If I hit the brakes with the pedal the slider marks go up a bit ( I have it set at 10) then return back. But if I hit the slider bar the trailer locks up. I know the 10 is high but I cant figure (nor can dealer) out why it does not work off the pedal. Also it shows nothing on the info board in the truck.

Any Ideas

it will not show on the info board. that was put there for the 09/10's. have you checked all your grounds on the trailer?

I agree with senix about a missing or loose ground being the HARDEST trouble to locate.<O:p</O:p
Which makes me think the trouble is in your F350.
<O:p</O:p
If the manual control works, using the ONLY ground and the ONLY power source going to the trailer but the normal operation of the controller =’s little or no brakes.
The trouble is in the truck.
<O:p</O:p
I would try a different trailer if available, JUST to prove your test procedure OR use a different truck, JUST to prove your test procedure.
<O:p</O:p
Then take it back to the dealer.
<O:p</O:p
ab

I had it there and they said they have simulators to test. which I doubt. I have 2 trailers and neither works right. but if I hook it to my work truck with aftermarket controller it works fine. I may have my friend come over and hook it to his truck to see what his does. He has an 08 as well.

Just take a long piece of wire and hook it between the negative battery terminal and a screw on the trailer chassis. If your problem goes away, you have a grounding problem. If it doesn't, its something else.

I really doubt it is a grounding issue. Even if it was after time and hauling the trailer would ground itself through the hitch. This problem never gets better. It never works

If it was a grounding problem, the brake controller wouldn't apply the brakes under any conditions. I'd suspect a bad signal to the controller, either brake applied/brake lights or braking force. They sense braking pressure, so it could be a faulty sensor thinking you're just touching the brakes.

Whenever you ground through the ball, there can be a rust coating which effectively increases the resistance of the connection. The effect of increased resistance is to reduce the current flow. The effect of reduced current on an electromagnet is to reduce the power of the throw, and/ or to create an intermittent electrical circuit, depending upon the extent of the rust/ grease.

Establishing a good ground is a quick, simple and easy approach for decisively eliminating grounding issues for diagnostic purposes.

I Agree. But trying to tell a ford supermechanic that is like well you know. LOL

Read my post right above yours- If there was a bad ground, the manual control wouldn't work either. Since he can easily lock the brakes manually, then the problem is not the ground or the controller. It is something on the sensing side of the controller.

I have done some research on the factory brake controller and what I have found that is a very complexed controller.
1 when your truck is not moving it only puts out 3 volts when manually pushing the lever to all the way to right

2 it uses speed and the amount of brake pressure to figure out how many volts to put out which in turn gives you brake signal to the trailer

Also if go to wikipedia and put in ford tow command you will find some more info on it

The True Proportional Controllers come in two types as well and are perhaps a fourth category for controlling trailer brakes electronically. The Ford Tow Command and the Sensabrake EVO are good examples of true proportional control. The Tow Command or a system integrated with the tow vehicle as original equipment utilizes actual towing vehicle hydraulic brake pressure to provide the signal to the brake controller. This transducer signal is then conditioned and sent to the brake actuator as a 0-12 volt output.
The EVO by SensaBRAKE uses a pad that replaces the rubber on the brake pedal of the towing vehicle. Contained in the pad are strain gauges that provide a signal that is proportional to the force applied to the brake pedal. The electronics then translate this to a 0-12 volt output for the actuator. Read out with trailer monitoring is included.

Hope this helps

Don't know that I can agree with that..... Hitting the brake pedal also engergizes a lot of wires and lights that the manual controller switch doesn't. If any of this bleeds through a corroded connector or merging of dual-lamp filiments to the trailer chassis, its possible to float the ground, which would reduce the current flow to the trailer brakes.

For instance, for instance, does the intensity of the trailer running lights (not the brake lights) vary when the brakes are applied?

Of course, if that its too much trouble too, he can always run out and replace the pressure transducer in the master brake cylinder....

This is a known fact and this is how ford checks this, it is done right at the plug on the truck.

Ha, not you 88Stang, my comment was in response to FordSix...

sorry I jump ahead of myself