Truck pulls to side when braking and pulling my trailer

Rickieblue wrote:
You surely have 1 brake that is not working. Stop and think about it, if there is more braking on the left side of the trailer it will pull the front of your truck to the right. Take it out for a ride and apply the brakes on the trailer a little bit..not enough to pull your truck around alot because you need to be somewhat safe .. another words be careful..after several miles get out and see if you can feel heat on the brake drums of the trailer..I bet you have one that is cold..it will have a bad magnet or a wiring issue. Report back and let us all know!!

For certainty, jack up each trailer wheel individually, pull the emergency brake pin on the trailer and see if the wheel locks up. If so, then OK and move on to the next wheel. Easy, positive way to determine if the fault is with the trailer.

Thanks for all the tips. I will try these and post the results. The ABS theories make sense but I'm hoping the problem is with the trailer - it would be cheaper to resolve!

If it were the ABS, he would feel the pedal pulsating and vibrating under his foot. Surely he would have mentioned this.

You should NOT feel pulsating and vibrating under your foot when braking unless you are on ice or making a *panic* stop. If your truck does that all the time to the point where you feel it is normal enough to not mention, get your ABS fixed.

There are some simple tests to see what is causing the problem:

1. Turn the brake controller down to 0. Now try stopping with just the truck brakes. If it pulls, it's a problem with the truck.
2. Set the trailer brakes where you had them. Now try stopping with just the trailer brakes. If it pulls, it's a problem with the trailer.

If it turns out to be the trailer, jack it up and spin each wheel individually while a helper operates the brake controller. You will likely find that one or more brakes are not working.

The truck is a 2011 GMC Sierra Denali 2500HD crew cab with 6 bed.

changed from a 26' 5th wheel to a 24' regular trailer

that truck should stop a 24' trailer just fine. take the unit and go find a large parking lot that is not being used after hours, on a day the business is closed etc.

you will need a big enough lot to get a little speed up, but you don't need to be on a race course. see if you can find the minimum speed the problem occurs at.

then unplug the trailer and see how the truck stops.

if the problem is still present, it is in your truck (or induced into your truck by the trailer being hitched to it). if the problem has gone away, it is the trailer and you can then go from there.

You surely have 1 brake that is not working. Stop and think about it, if there is more braking on the left side of the trailer it will pull the front of your truck to the right. Take it out for a ride and apply the brakes on the trailer a little bit..not enough to pull your truck around alot because you need to be somewhat safe .. another words be careful..after several miles get out and see if you can feel heat on the brake drums of the trailer..I bet you have one that is cold..it will have a bad magnet or a wiring issue. Report back and let us all know!!

If it were me, I'd get one of those infra-red thermometers, take a drive with some braking, and then check to see if one or more of the trailer wheels are colder than the others. That would indicate a brake not working. That would have a tendency to push the rear of your truck to one side. I had that problem after I changed the brakes on my 5th wheel, and it turned-out one of my connectors was not making good contact.

Yes, it sounds like the ABS on your truck. When towing the trailer's momentum is still pushing forward (even if the trailer brakes are locked down). The ABS is reacting now, like it would if you were on Ice or a slick road. They react and put more resistance on the wheel that will correct a skid (so it thinks). Your ABS thinks your in a skid and attempting to correct, but it's not really on ice or wet roads, it's the push of the camper from behind. But the ABS does not know this, it's just sensing a skid in process.

I don't think there is any way you can test this theory, even if you set your trailer brake controller to lock-up the brakes, the momentum of the camper will still push forward.

Switching campers and switching tow vehicles is a very good idea. It will determine immediately if the problem is with camper, or truck. I think you'll find it's the truck.

Edit: in a nutshell, your truck to too small for the camper. It can't stop it.

Edit Edit: I re-read your post again, and still think this theory is right. When you towed your 5er, the 5er was much heavier. When you applied the brakes on the trailer, the sheer weight of the camper pressing the tires into the road caused enough friction to counter act the forward momentum of the truck. The lighter camper does not have the same friction on the tires against the road. Being lighter, the brakes will not engage as strong, allowing for that forward momentum, thus causing ABS to think its in a skid. Does this make sense?

Just thinking out loud. On a 5th wheel trailer very little weight is transferred to the front of the vehicle. But with a bumper tow about 25% of the weight is transferred to the tow vehicle. Just wondering if it is an alignment problem with the truck, that shows up with the extra weight on the front end.

When the dealer did "all they could do", were they testing with your P/U, or theirs? If theirs, then I would tend to agree that there may be something going on with your truck, or minimally, the wiring connection between your truck, and the trailer. Is the brake controller a built-in, or add-on? Maybe not getting good enough connection between your truck round plug, and the trailer connection. Is the gain turned up high enough? Could it be the trailer pushing the truck?

Do you have a second vehicle that you do a test tow with? Or does a friend have one? You need to narrow the problem down by eliminating either the truck or the trailer as the problem.

What happens when you use the hand controls to apply just the trailer brakes? A technique I use occasionally when I adjust my own brakes, is to take it for a test drive, and intentionally "heat the brakes up" by using the hand controls, and then stop to see if they are all about the same warmth, indicating that they are all adjusted about the same. You could use that same technique to make sure all wheels are contributing to the stopping process. just a thought.

I don't know, just questions.

I knew something was wrong when my empty 16' car hauler caused the truck to yaw during brake application. I had a failed magnet on one side (only 1 axle has brakes).

Having 2 braking axles, I wouldn't imagine a loss of one on one side to cause as much of an upset, but maybe it could. The fact that it wants to go either direction concerns me.