Or hook up to it do about 30 and hit the brakes hard, if the trailer locks up decrease the power.
you guys might laugh, but for a guy who has never played with a brake controller, this is a real good way for him to do it, except hitting the brakes hard.
i tell guys that ask me this ?, this. you know how your truck feels unloaded. what it feels like stopping.
you should not feel the trailer behind you, when you hit the brakes. if it "takes you longer to stop", turn the controller up. if you feel it "slowing you down faster", lower the setting.
you have a progressive controller in your truck, not a fixed one. what this means, is the harder you push on your brakes in the cab, the harder your brakes will apply on the trailer. on a fixed controller, it doesnt matter how hard you push the pedal, the brakes will apply a set amount, regardless if your having a "o chit" stopping moment or not.
what this means, is when you apply the brakes normally, in a normal slowing down scenario, the trailer brake controller should not be 100% maxed out. that means your trailer is not doin enough, as your having to mash the pedal to get it to stop. in your dash you can set it so you can see that. there will be a row of bars you can watch rise and fall based on how hard you push on the pedal.
try to set it to somewhere in the half way point. this way, if you have a "o chit" stopping moment, you still have additional trailer brakes available to help you stop, just like you have additional pedal left.
keep in mind, that your number for your brakes, will be different loaded vs unloaded. potentially different for in town vs country. different for a hilly road vs flat ones. different for different weights of trailers. different as the brakes wear out and need adjusted/replaced. different based on where the load is on the trailer, does the trailer have most of it, or does the truck, or is it even.
dont be afraid to change it as you drive till you get it to where you like it. eventually you will get to where we are. i know that my goose neck trailer is 8.5, my dump trailer is 7.5, and my flat bed is 9.5, and my cattle trailer is somewhere between 6 and 10 depending on whats in it, all when they are loaded. when unloaded they are all 3. i dont have to even think. get in, set my number, drive.
before you really take your trip, take it out on the road, and set the controller on 1, and see what it feels like. you didnt state what it is your pulling, but you should see a noticeable increase in stopping distance, as the trailer isnt doin hardly anything. then set it on 10, and make the same stop. you should really feel the trailer brakes biting, if not locking up the tires. get a feel for just how hard you "can" have the brakes apply. obviously you dont want them this hard, but to get a feel for what were saying, its a good learning experience. learn what both extremes feel like, so you can find your happy medium.
on my dump trailer, with a partial load on it, and my controller on 10, if i apply the brakes hard, i can literally make myself eat the steering wheel, they will apply that hard, and everything will stop that fast. will everything in correct adjustment, and fresh brakes, you can potentially make it stop faster loaded, than unloaded. yes, you read that right.
it should also be noted, that if at any time you see or feel the trailer brakes lock up, you need to lower the setting on your controller. i know that should be obvious, but it still needed to be stated.
to change the setting, apply slight pressure to the pedal and make the controller light up, and push the appropriate button on the controller, either the - or the +. you will see the number change.
it should also be noted, that if the brakes on the truck fail, for some reason, pushing on the brake pedal will
NOT apply the trailer brakes any longer. right under that +/- sign you will see two little "handles" you can pinch together with your fingers. this will also apply your trailer brakes. to a max of whatever number you have it set on. if the brakes on the truck fail, your e-brake and these two handles are the only things goin to stop you now.
this is also a good way to get a feel for the trailer brakes. drive down the road, and do not push on the pedal. pinch the two "handles" together. you will feel your brakes apply.
hope that helps.