Integrated Brake Controller/Gain issue?

[MrMike1289]

Hey all! I am fairly new to towing, especially with my 21 Yukon with the duramax. We bought our trailer earlier this season. This last trip we took the trailer on, we ran into a strange issue with the trailer brakes. Normally we keep the gain set to about 5. However, coming off an exit on the freeway, the trailer brakes locked up. After doing a little testing here and there while on the road, I discovered that I had to adjust the gain down to 2 in order for the brakes not to lock up on me. Then, just a while later at another braking opportunity I noticed that now the trailer brakes were too weak and not helping stop the trailer at all. So I adjusted the gain back to 5. I’m finding I need to keep adjusting back and forth between 2 and 5 to keep the brake strength set right. Keep in mind this is all the same exact trip, not adding or subtracting weight. I’m not sure if this could be a trailer issue or potentially something wrong with my trailer brake controller? I’d love to hear your thoughts before I bring this up to the dealer.

Side note, the last site we set up at, I noticed one of the RV batteries was boiling (as they are probably 6 years old now). That’s a whole story in of itself.. however we disconnected the bad battery since. Could this have something to do with the inconsistency in the gain?? We are still having the inconsistency issue with the gain after removing the bad battery.