Trailer brakes locking up even with a slight brake application

Hello everyone,

I have a Mac Roadwarrior flatbed trailer 2009, where all the wheels lock up everytime I apply the brakes, no matter the brake force applied (slight, normal or heavy). My Truck is a Western Star 5700XE 2016.
I have pulled the trailer with a different truck, same problem.
The problem started after I had new brake shoes installed (otr 4707q green 23k). I weighed the trailer axles individually and the weight was the same. Brought the trailer to different shops. They all tell me it's this or that but so far none of the parts they replaced have fixed the problem. Trailer has new brakes, new drums, new ABS relay valve, 2 new ABS sensors, and new suspension bushings and still the same problem.

Please help

Thanks
Roman

 

The Trailer is a 2009. Weight was 3540 lb on back axle and 3480 lb on the front.
The brakes have still the stickers on it OTR4707QGRN. All I know is that this shoes are recomended for flatbed trailers.

 

Did your trailer lock up empty and loaded? Mine does

 

The Trailer is a 2009. Weight was 3540 lb on back axle and 3480 lb on the front.
The brakes have still the stickers on it OTR4707QGRN. All I know is that this shoes are recomended for flatbed trailers.

 

The trailer is equiped with a Haldex slh-a7.
I don't understand how ABS could cause the wheels to lock up? Shouldn't ABS step in after the sensors detecting a wheel lock up?

 

Trailer has the correct brake shoes installed (4707 Q Plus) . I checked today with the trailer manufacturer to be sure.