Breaks and/or drive train. It is available for inspection. 1) Breaks sink causing slowed break time and decreased breaking ability. If the breaks are "pumped", more often than not, they will come back up to full pedal. However, in an emergency breaking situation, there is not time to "pump" the breaks. I was nearly in an accident recently when the break pedal would not stop the truck in time, due to the soft break pedal. I literally had to steer to the shoulder of the road. 2) When placing transmission in Drive or Reverse from the park position, then taking foot off of break pedal, there is about a 1 - 2 foot roll, then the truck stops as if the e-break has been engaged (but it is not engaged). By tapping the accelerator, it will "break free" (with a popping sound and a slight "jerk" in the truck) and then roll fine. This does not always happen ~ guestimate of about 10% of the time. 3) I don't know if this is related, but when I set the Drive Mode to "Normal", it automatically goes to "Off Road" ~ this happens no matter the driving conditions. This isn't safety related necessarily, however, it may be a part of the total problem.... It also decreases my fuel economy. I took the truck to the local GMC dealer/shop. They said the truck had 2 recalls and they took care of those. They believed one of the recalls would help solve the "sticking" when placing in Drive or Reverse ~ it did not. They also (supposedly) checked the breaking system and took it for a test drive. They said the breaks were fine. I doubt this happened as the soft break pedal and the need to "pump" the breaks to bring them to full pedal is completely obvious. I took the truck home after the inspection and recall. The same issues continued, so I took it back to the shop where it was inspected again. Again, I was told everything was in working order ~ it is NOT! There are no warning lights that I can find to indicate there is an issue. I'm begining to think that I should have bought a Ram Truck...

- Lebanon, OR, USA

The truck disengages the 5th wheel trailer brakes. The DIC states "Trailer brakes disabled - service required". I intermittently lose trailer braking capability.

- Oakdale, IL, USA

The in cab brake controller does not work with electric over hydraulic trailer brakes. In my research to diagnose and fix the problem I find out GMC has known about this for years and has done nothing to correct. I pulled code C1114 and GMC issued a bulletin for part number (K58-036-00) which I purchased and still did not correct this issue. In short there are many 3500 trucks out there running with no trailer brakes. Here is the worst of this problem. If brakes are tested at a stop they appear to work perfectly however once driving this is when the error code is delivered to the truck so the brakes work at a stop when not needed and do not work under driving when they are needed. GMC has ignored this for years and after spending more of my hard earned money for a fix that did not fix the problem. Below I had to choose a date however this has been an issue since first purchase December 5th 2023 to present.

- Fort Garland, CO, USA