Weak Trailer Brakes

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plankey

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I have a 2018 FX4, XLT Expedition. My problem is after plugging trailer to suv the lights work fine, and the trailer brakes work, but are very weak. I set it up through computer to brake hard, and have the gain turned all the way up full to 10. I can feel the trailer brakes engaging and disengaging, but it’s very weak. Every other truck I ever had, when turned all the way it would lock up the trailer tires. It won’t even come close to doing that even with the trailer empty. It does this no matter what trailer I hook to it. Am I missing something here?
 

MTB2022

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when was the last time the trailer brakes were adjusted out. They are not self adjusting and become less effective as they wear and the distance between the shoe and drums increases.....just a thought.....
 

LG_123

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I agree, it sounds like an issue with the trailer brake setup. If they’re activating but not working well, they need to be serviced.
 

LazSlate

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Test the voltage on the connector with the gain up to full (manual gain)
The #2 blue using #1 as ground. Then compare to normal charge power pin #4 red.
Red will be the max power coming out of the jack and the blue should be close on max gain.

99% of the time it something with the trailer even new trailers sit and the drums rust or get condensation.
Some just do not have good brakes to begin with. I had a quad wheel car carrier and it only had brakes on 2 drums and it was always weak. i added brakes to the other 2 wheels and made a night and day difference.
 

Rossue

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New trailer brakes have to be burnished in. Lippert has an excellent video on how to do this.

When I replaced my trailer brakes they were weak until I did the above. Also be sure they ar adjusted properly. The wires on new trailers at the brakes can be faulty too.
 

Meeker

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On my 2018 with HD Tow (including the trailer backup assist), when you set up the trailer in the "Towing" menu, there is an option to set the "brake effort level" either low or high. Low is the default. This setting is in addition to the 1-10 level using the +/- buttons on the brake controller. Try setting it to high and see if it helps. This requires setting up and saving the trailer settings, and that trailer setup must be active.

If you already did this, then you should be looking at the brakes themselves as others have suggested. Could be anything from poor connections/high resistance in the wires, mechanical issues in the brakes themselves, etc.
 
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