brakes locking....suggestions?

Had this issue with my prodigy controller the last time out. FWIW, I am towing a Jayco White Hawk 28dsbh with a 2012 Tundra. On the way to the campground I was using boost 2 with no issues. On the way out (after a full week, during which it did rain and with excessively high humidity all week), the brakes were locking up. I switched to boost 1 and had no issues.

B2 is pretty aggressive.

The instructions give you a starting point. From there it's up to you to experiment and see what works best for you.

Solved - turned off the boost feature on the P3

Just picked it up, so new to you and ask if bought used or is it brand new, as
that makes a difference in forensics of why it is locking up

Just some things that might be the cause

Brake fluid and some oils when contaminated on friction materials can cause the
shoes to bite hard and lock up. Know that is weird, but that is in the book but
never experienced that

Of course rust, but not again in a couple weeks...unless you have it stored in
a high humidity location and/or salts got on the cast iron....of course assume
electric shoe/drum brakes and not some newer setups with disc on their trailer brakes

Adjustment. Since shoe/drum has a self wedging (they call it self energizing, etc)
If out of adjustment, the wedging action is exacerbated by the shoes having to
move a larger distance, there fore the angle of attack is high to cause it to bite
very hard and lock up

Controller and yes dial it back all the way with no boost, etc and test it

I also have a P3, have no problems and love it.

You have a Silverado, so the best brake pedal switch as mine (assume GM hasn't
change it since my 1996 Sub).

Properly setup, my Sub can stop both trailer and TV WITHOUT moving the brake pedal
far enough to develop braking on the TV (zero PSI in the master cylinder).

My setup has the trailer lead the TV in braking, so smooth and seamless

Tell us a bit more about the trailer. New, used and if used, when was the brake
system checked

I'm confident the issue is with the controller....either the setting is wrong or my choice of a mounting location isn't the best With the boost setting off, the trailer stops fine. I set the boost to B2 and with a small amount of pedal applied, the output shoots to 6ish and drops back to zero, repeatedly ...no gradual or phased output as I would expect. I did mount the controller on my ash tray door for better visibility...I try to move it to under the steering column and recheck my settings.

Don't necessarily have to adjust the controller every time but they should be cleaned and warmed after sitting for a bit. Ever leave your car sitting for a few days when it rains? The brakes grind for a bit as the surface has rusted a bit. Same for your tt.

I use the manual lever on the brake controller to "drag" the brakes slightly as I pull out of the storage lot. They no longer stick and grab by the time I get on the road.

All good advice above. If you brakes are locking up you have some sort of wiring malfunction/brake malfunction, or a mal-adjusted controller, or all of the above.

Trailer brakes aren't rocket science folks; you hit the pedal and voltage is delivered to you magnets to drag the brake drums to a halt. It's a very dumbed-down braking system that should not be difficult to diagnose.

you need to turn down the controller and warm the brakes up while adjusting the controller EVERY TIME you use it if it has sat awhile.
read your controller instruction manual it will give further details of the procedure.

I'll take it back to the dealer before I tear into it....the trailer is still under warranty. I was hoping someone had a similar issue with the break controller.

Start taking things apart and inspect each brake assembly.. Something is not right.