TT Brake Service

alexey75 wrote:

JBarca wrote:

alexey75 wrote:

JBarca wrote:



OK, I know the self adjusting trailer brakes.

1. Do you "only" feel the "jerking", whenever it happens, occur when you are applying the brakes and then "stops jerking" when you stop applying the brakes?

2. OR, does the jerking start when you have applied the brakes, and may continue for a short while even after you stop applying the brakes?

3. The key point it, the issue "starts" with a braking action, yes or no?

Please answer all 3.

John

John,

We bought this trailer about a year ago, and during the summer I've experienced it probably 5-6 times.

1. It happened when I have applied the brakes during the slow down, like before the traffic light. When the speed was around 10 mph I've felt the jerking for a second, just before it came to full stop.

2. No, it didn't happen when I applied the brakes. And it didn't continue when I stopped applying the brakes.

3. No, it doesn't start with the braking action.

I've mentioned before, I've read in truck's manual that the truck stop applying the TT brakes when the speed below 12 mph (or something like that).
Any chance it's related to truck and not trailer?

What year, make and model truck do you have? I looked and cannot find it in the thread or your profile.

Does the truck have an integrated brake controller or an aftermarket one? If aftermarket what make and model.

Not sure I ever heard of a brake controller that stops working on the way down in speed. But it maybe, not sure why though.

And yes, some integrated brake controllers do drop off current while the truck is standing still and you have your foot on the brake, but by then you are stopped and not moving.

Thanks

John

PS, this one is a bit of a mystery as it seems to point to only low speed, please confirm, it is only low speed coming to a stop. I'll hold off on speculation until we know more about the truck and brake controller. I have had trailer brakes do strange things that sort of lock up creating some of what you are describing , but not with this only low speed issue.

It is 2018 f150 with integrated brake controller.

Found it :)
The trailer brake controller is equipped with a feature that reduces output at vehicle speeds below 11.2 mph (18 km/h) so trailer and vehicle braking is not jerky or harsh. This feature is only available when applying the brakes using your vehicle's brake pedal, not the controller

https://cdn.dealereprocess.org/cdn/servicemanuals/ford/2018-f150.pdf
Page 308

OK, there is a difference between "stops applying" below a certain speed and "reduced output" below a certain speed.

I have the first generation 2005 Ford intergraded brake controller, the one that will not allow the manual lever to work until the truck has gone over I "think" like 15 mph. It will let me manually brake to zero speed, just not on the way up. There was so many complaints on this that after Feb 2005 builds dates, they will apply brakes manually at zero speed.

And mine does reduce output once I am stopped.

Your 2018 has more setting then my vintage and it may be part of the issue you are having if it doing it's thing below 11.2 mph. Search around and see if other Ford 2018 or newer has this issues. There may even be a TBS about it.

Curious how this comes out.

John

PS. Reading page 308, 2 bullets up from the reduced output state, See here: https://cdn.dealereprocess.org/cdn/servicemanuals/ford/2018-f150.pdf

Ford is now saying you are not supposed to press the manual brake controller button if the trailer starts to sway. They are stating that is "misuse". Ford now states to only use the manual button for setting the gain. I'm not sure I agree with that. Pressing the manual button while driving straight ahead, and on purpose not using the truck brakes, used to be the first instinct go to action to help tame out a swaying trailer. I have not heard until I saw that tonight. WOW..!!! Do other brands of integrated controller now say this?