Violent jerk while towing.

[Optimus Prime]

We have a 2021 GD Solitude S-Class 3540GK that we absolutely love. We are, however, experiencing and "out of the blue" violent jerk while travelling down the highway. It feels like we are towing a car behind us with a heavy chain that gets too much slack in it. When the slack is quickly taken up there is that shock that jerks us out of our seats. We thought it may be the brake controller from our 2020 GMC 3500HD Duramax w/10 speed transmission, so we pulled the fuse to the controller. Thought we had it licked but the issue returned. Does anyone have any ideas? We areis South Dakota and have to make it back to Oregon.

[Jkwilson]

I’d be checking the hitch and pin box closely for anything loose. Then take a look at the suspension of the trailer.

[Yoda]

We have a 2021 GD Solitude S-Class 3540GK that we absolutely love. We are, however, experiencing and "out of the blue" violent jerk while travelling down the highway. It feels like we are towing a car behind us with a heavy chain that gets too much slack in it. When the slack is quickly taken up there is that shock that jerks us out of our seats. We thought it may be the brake controller from our 2020 GMC 3500HD Duramax w/10 speed transmission, so we pulled the fuse to the controller. Thought we had it licked but the issue returned. Does anyone have any ideas? We areis South Dakota and have to make it back to Oregon.

John is correct
Do a pull test (forward and back by locking/blocking the trailer) and have someone watch the king pin on the hitch for movement. What hitch do you have? The reason I ask is there was a post on jaw movement, but I forgot the brand. Also check the hitch attachment points. Are you using a puck or rail system, or just the goose neck ball mount.

[Canyonlight]

Optimus Prime - good suggestions so far. Your situation is unusual as you describe it. Where are you at in SD ? If close to Sioux Falls in the SE part, I may be able to stop and take a look if you do not get resolved and still need assistance.

How long have you had your 3540 ? Just got it and/or a new hitch ? A new condition just happened or has been happening for how long ?

Dan

[TucsonJim]

Another item to check.

Take a good look at the plunger on the break-away switch. If it is not securely snapped in place, it can randomly apply the trailer brakes. I'd pull the plunger all the way out, and then make sure you reinsert it so that it's firmly in place.

Jim

[Cheryle]

I bet Jim’s right - happened to me with my break-away switch and it was very scary.

[Scott'n'Wendy]

Another item to check.

Take a good look at the plunger on the break-away switch. If it is not securely snapped in place, it can randomly apply the trailer brakes. I'd pull the plunger all the way out, and then make sure you reinsert it so that it's firmly in place.

Jim

Good idea. Seems a very likely cause to me.
If it happened to me I'd have to stop and do laundry!

[Yoda]

Another item to check.

Take a good look at the plunger on the break-away switch. If it is not securely snapped in place, it can randomly apply the trailer brakes. I'd pull the plunger all the way out, and then make sure you reinsert it so that it's firmly in place.

Jim

I never would have thought of that
Keith