1 wheel locks up when breaking help!

I am going to have to agree w/DD here--I'm betting it is in the proportioning valve--now w/abs trailer--they are kind pricey(@least on a dane--it is one unit valve/abs--but you can run a regular 4/6(depending on set up)this valve isn't very hi-dollar--If it was me I would leave the original valve(and wires if ABS)intact and re-plumb system through one of the standard(cheaper)valves--if that solves it--you can run that way till you get the right one(w/abs) and then just return to spare one you bought--I know it's BS parts changing 101--but it can be a cheap easy diagnostic and fix.
Just my$.02

 

could be grease on shoes (wheel seal) or worn s cam bushings

 

OP said that the shoes were swapped so unless he disturbed/tore a wheel seal

 

Thats what I did and it solve the problem. I had the same problem but it was the front axle on my trailer that locked up when I was empty, and I didn't add the quick release, there was no need too.

 

We had a trailer once that the rear axle air bags were not inflating and the brakes would lock up all the time simply because there was no weight on that axle.

 

A friend of mine had this same problem today on his Coranado.I was there at the shop when they pulled wheels and drum off.The problem was the S cam shaft was seizing.Hope this helps.