3 axle break controller issues

Question

I have a 2019 Sierra HD with integrated brake controller. I'm towing a 5th wheel camper with two axles and electric brakes on each. Behind the camper I'm towing an ATV trailer with two axles, but only one of them has an electric brake. Towing either of the trailers individually there are no issues with the trucks brake controller to control the brakes on the trailer. But with both trailers connected the truck won't apply any 'juice' to the brakes. It does nothing - no brakes on their trailer. When I manually apply the brake controller it does nothing. GM is telling me the truck is only designed to handle two sets of electric brakes and if I want to handle 3, I would need to add an after market controller to control the 2nd trailer separately. I can understand not having a powerful enough controller, but does it make sense the trucks computer/controller would not apply any 'juice' to the brakes when it senses too much resistance via the 3 sets of brakes? Has anyone had this issue? How did you resolve?

I've never towed a 3 axle trailer before, but assuming all three of those axles have brakes don't they? How does the controller work in those instances?

roger10378 · Answer

You don't say how the brakes are wired to the second trailer so it is hard to know what is wrong but I think the problem is in the wiring between the two.

I can't think of any way that type of setup would work even if the controller would supply juice. There is no way that you could adjust a controller to supply the different amount of voltage that would give each set of brakes an appropriate amount of voltage. One would always give more brakes than the other. If you were to adjust it so that the 5er brakes give a decent amount of stopping power you would lock up the atv trailer or vice-versa.

mike134 · Answer

My guess the 3rd set of brakes draws too much current for your OEM controller.

https://www.hitchweb.com/blog/post/2012/02/21/testing-trailer-brake-magnets#:~:text=Testing%20Trailer%20Brake%20Magnets%20%20%207%22%20Brake,%20%20%20%203%20more%20rows%20

ferndaleflyer · Answer

I have a 3 axel trailer and the factory controller on my F-350 works perfect.  It also worked on my previous 3500 Chev.  That set up you discribe sounds like a disaster waiting to happen....and now brake problems?

kd4upl · Answer

I have no idea why your set up won't work but you don't want to do it like that anyway. You need a separate brake controller for each trailer. Use the built in for your first trailer and install an aftermarket one for your second trailer. You will need to adjust each independently to get everything to stop straight.

Incidentally, having more brakes connected does not increase the resistance (assuming you wired it properly) it will actually decrease the resistance causing the brakes to draw more current than what 2 brake axles would.

dkuntz · Answer

Great input - I agree the 2nd controller makes sense now. I still don’t know why the truck is deciding to not send any voltage....not the best default if you ask me.

I tied into the 5th wheel wiring in the front compartment before it went into the under belly and then ran a new 7wire all the way to the back of the 5th that the ATV trailer then plugs into.

Thanks for the input!

Forum Discussion

3 axle break controller issues

About Fifth Wheel Group

Related Content

Spongy breaks

Dometic Comfort Control 2 Thermostat issue

Disc Breaks

emergency breaks

Bedroom slide breaking shear pins