3500hd trailer brakes issue

Metal.Dave · September 27

So I'm having a weird issue with my 2021 sierra 3500Hd trailer brake controller. The issue:

- Hook up trailer #A, when empty brakes needs to be set below 3 to keep tires from locking up.

- Hooks up trailer #B, also empty, turn up controller to 10 and I barely feel any braking force from the trailer when manually pushing the slider all the way. I can hear the electric brakes working on the trailer, it's just not giving enough braking force.... so it's not the same issue that others are having where it's not working at all...

-No error messages on dash.

- both trailers are dual axle and have about the same empty weight.

>● If I hook up either trailer to another truck at the yard (Ford or ram are the only other options) the controller needs to be set at 3 or below also to keep tires from locking up. This test rules out any trailer issues!

I have searched Google and the forums and could not find any solution! Some people have tried replacing the sliding push control in dash, No luck. Browsed through hundreds and hundreds of forum posts, no solution found......

bruceb58 · September 27

I would do a couple things...pull trailer wheels and check brake condition and if they are adjusted properly.

Double check all wiring and make sure you don't have a bad connection somewhere. If possible, measure voltage at each brake magnet while someone pushed the manual lever.

I am not convinced that your trailer is not the issue.

Metal.Dave · October 21

On 9/27/2024 at 3:25 PM, bruceb58 said:

I would do a couple things...

I am not convinced that your trailer is not the issue.

I am convinced that the trailer is not the issue because I can hook it up to another truck at the yard and it works just great!

It seems as if though truck has some intelligent system for detecting trailer brake types and adjusting voltage output for those kind of brakes but theres some inherent issue with the technology....

64BAwagon · October 22

You dont mention what year the other trucks are that youve "tested" the trailer on. The 2021 has a sophisticated trailer control module compared to most trailers and earlier trucks. If theres even a slight fault in the trailer wiring it will not function properly. Its like trying to use 8 track tapes (if you know what they are) with an SD card reader. The fact that your trailer A works with the truck is an indicator that the truck is okay and that trailer B has a wiring fault of some kind. You wont find a magic answer on the internet, this will require some diagnostics

Since you asked, I would look for ground and or damaged chafed wires on your trailer. If its near time for a bearing repack I would look the magnet wiring over while in there. Do the cheap and easy stuff first.

Your other option is to have the truck checked out and that will require a shop or dealer with the tool to do that on newer trucks. That one will cost you.

Edited October 22 by 64BAwagon