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Discussion Starter #1
I have a 2018 Duramax 3500hd and pull a 2017 Jayco 28BHBE. When I first got the truck, when setting the brakes, I could lock the brakes at a setting of 4.5-5 when manually applied on gravel. Last summer something went away and even bumped up to 10 I couldn't get the brakes to lock. This spring I took the trailer in to the RV place and they said it was fine. I later had a auto shop plug in a cheap checker which showed everything was working at the switch. After taking a trip, I still didn't feel I was getting full braking assist from the trailer then noticed once, while driving on grass, I manually applied the brakes and only the front axle locked up. I took the trailer in again. I've been told when they tested it, both axles tested equal with both braking the same. The RV place told me to have my controller checked.

My question: Why would a controller issue cause one axle to brake and not the other? Any other ideas anyone can suggest to have looked at? We've moved to a new area just outside of Spokane so I can try to take the truck into a dealer, but it's not really convenient thus if there is an obvious thing I may be missing to check first, I'd love to hear it.

Thanks!
 

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I have a 2018 Duramax 3500hd and pull a 2017 Jayco 28BHBE. When I first got the truck, when setting the brakes, I could lock the brakes at a setting of 4.5-5 when manually applied on gravel. Last summer something went away and even bumped up to 10 I couldn't get the brakes to lock. This spring I took the trailer in to the RV place and they said it was fine. I later had a auto shop plug in a cheap checker which showed everything was working at the switch. After taking a trip, I still didn't feel I was getting full braking assist from the trailer then noticed once, while driving on grass, I manually applied the brakes and only the front axle locked up. I took the trailer in again. I've been told when they tested it, both axles tested equal with both braking the same. The RV place told me to have my controller checked.
I think you've been lied to.

My question: Why would a controller issue cause one axle to brake and not the other? Any other ideas anyone can suggest to have looked at? We've moved to a new area just outside of Spokane so I can try to take the truck into a dealer, but it's not really convenient thus if there is an obvious thing I may be missing to check first, I'd love to hear it.

Thanks!
No reason at all, since the brakes are on the same circuit and therefore the controller just sees them as one big load (teehee!).

There are basically two potential explanations here, each of roughly equal likelihood.

The first is electrical, i.e., there's increased resistance on the bad axle. This can be difficult to test but I'd give a cursory glance at the wiring and make sure none of the connections look/feel loose.

The second is mechanical, i.e., the brake shoes are not adjusted properly. You can probably find the adjustment procedures online if you look around a bit.

Okay, fine, it's possible that the brake controller is not putting out sufficient voltage under load and an otherwise-imperceptible difference in electrical resistance or brake shoe adjustment has become noticeable. But I'd say this is extremely unlikely since it's putting out enough juice to lock up one of the axles. These kinds of problems are almost always the trailer's fault.
 

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Discussion Starter #3
Thank you jd. I was of the same opinion as well that if I had braking on one axle, it should also be working on the other.
 

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I agree if the signal “voltage” is going to the trailer then your controller has done its job. There’s something going on with the trailer itself.


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You might try checking voltage at the lead behind each trailer wheel while someone engages the brake. Or you can pull the pin out of the break away switch if you are by yourself. Check this across the plus and ground wires, and also check between plus and the chassis.

I had both axles replaced on our TT and 6 months in I had similar problems. Found one of the hot wires bare where it goes into the axle tube. It actually went thru a grommet to prevent this but it was damaged on installation. I rewired both axles, running outside the tubes, and added a supplemental ground between the axles.

Each axle comes pre wired on the 2 wheels. There is only one hot and one ground from the front of the trailer to the axles, and this is spliced to the two leads from the two axles. This makes for a big set of splices and might be a problem area depending on what type of splices fitting they used.
 

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You might also try pulling the hub to see if the seal is shot and the shoes are covered in grease.

If it has grease through hubs, you are supposed to turn the hub while pumping grease manually and slowly to prevent grease from getting past the seal and onto the drums.
 

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Google how to re index your campers brakes. You are supposed to do it after the first few hundred miles

I don’t think it is your truck



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Although its unlikely but, when GM first installed the OEM brake controller, there were plenty of issues / complaints on the controller, I think w the 2012/2013 models, on multi axle trailers. Mostly on 3 axles but a few on dual axles. Controller worked fine on single axles but the dual and triples the controller worked poorly... Enough that guys were bypassing the oem controller and installing aftermarket controllers.. Just a thought... Have you hooked up your trailer to another truck? friends perhaps and test the brakes?
 

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You can do a amp draw test. I believe each brake draws 3 amps for a total of 12. Should be able to verify that with Dexter Axle who likely made the brakes.

Have you checked the adjustment on all the brakes? Like getting the trailer off the ground and adjusting the adjuster wheel till you can’t spin tire by hand then backing off till a light drag? You could also pull the emergency breakaway and see if it locks all 4. I would try this while wheels are off ground.

I would bet the most likely scenario is one of the connections going to the second axle is bad or intermittently working. I would double check connections and give them the tug test (lightly) to ensure they are solid connections.

Last idea would be if you were not hauling level. If your trailer was nose high or low it would have more pressure on one axle and less on the other. The one with less weight might skid much sooner if this was the case. You would also be much more likely to bend an axle if this was the case. Too much weight on one axle means it takes too much of the stress of bumps and bend.

If you do end up replacing brakes in future I would get self adjusting brakes to make sure they stay dialed in.
 
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