Troubleshooting Trailer That When Towing Gooseneck Brakes Erratically  

I have an issue that is occurring with my vehicle/trailer when braking that is extremely violent and only occurs while towing a gooseneck And it happens with every gooseneck, though some more than others. It does not happen with any of the various bumper pull trailers loaded to many different capacities that I have pulled. The truck also drives fine when not towing. Some basic info and history -Tow Vehicle: 2011 GMC Sierra 2500HD 6.0 liter gas 2wd Crew Cab 6.5ft bed It was bought used at a dealer with less than 30k miles on it and towed its first gooseneck under my ownership at approximately 38 - 40k miles. This problem has existed since the first time I towed a gooseneck. The Salesman at the Dealership had said it was purchased new from them by a guy that works in the oil fields who traded it back in for a diesel. It had the BandW gooseneck hitch in it when I bought it. -Trailer: Various gooseneck trailers This Issue has been present in my truck since the first gooseneck It towed under my ownership at around 38k miles... It now has 86k miles. -The problem is: When I am towing a gooseneck trailer and I apply the brakes of the tow vehicle to stop I get a very violent and pulsating thrusting and shaking throughout the truck and trailer as if the trailer is forcefully shoving the truck but in a pulsating rhythm. It can actually be so violent as to cause the rear wheels of the truck to break free and cause a fish-tailinch to occur. It will increase in intensity as if being amplified until you either release the brake or the vehicle has came to a complete stop. It will actually prevent you from stopping and it will either keep pushing you and it will shove the truck right off the road or into the other lane if you do not release the brake or you have to break in short intervals of gradually applied brakes increasing your braking distance drastically. This happens with normal breaking and tends to be worse in emergency breaking i.e. car pulls out in front of you and you have to slam on the brake. though it doesnt always occur, it happens about 85 of the time The truck has not had new brakes on it yet. And no ABS or traction control lights have ever came on while I have owned the vehicle. Has recently had new tires and the problem occurs with new tires the same as the old tires. Things I have tried/checked but hasnt resolved the problem 1. Turned rotors at 80k miles This did make the truck brake ALOT smother under normal/unhitched driving conditions. But not a fix for towing. 2. Had the BandW Goosneck hitch checked for loose or broken bolts and excess movement. Hitch dealer says it appears to be installed correctly and no signs of hitch moving against the truck frame 3. Checked brake controller it is working Although the applied brake force is weaker than Id expect. A couple of other vehicles controllers will apply enough force to lock the trailer brakes mine applies only enough force to slow the wheels and will not lock them. Gain is set to highest level of 10 4. Tried towing with the trailer brakes both disconnected and connected with no noticeable difference *However if I brake with solely the trailer brakes the issue doesnt appear. but my controller doesnt apply enough brake to the trailer to completely stop without the aid of the truck brakes unless you have an entire runway to stop on. 5. Tried several different gooseneck trailers all of which were dump trailer or roll-off dumpster trailer style. All trailers had the issue although some were noticeably better/worse. 6. Have tried loading all of them in different ways i.e. weight spread even, heavy to the back, heavy to the front, heavy over trailer wheels, etc with no apparent effect on braking issue. 7. I have also tried the trailer on another truck and it has no problems ANY Ideas on what the problem could be??

asked by: Josh C