2000 K2500 with FF rear end, brake issue while plowing

I was out for around 15 hours plowing last night. Noticed about 8 hours in that the back brakes would lock up with even the slightest application of the brake pedal, as well as squeal just before I came to a stop but only in reverse. It didn't do it all the time, but I'd notice when I was pushing/working it hard/spinning tires, it would start doing it. I would go to a different lot and it would act fine again. I pulled the ABS fuse just to see if it changed anything and it didn't. It would only do it if the truck was on snow/ice/slush, they would not lock up on wet cement. It seemed to have went away and stopped completely 4-5 hours after I noticed it the first time.

We got about 5" of basically wet concrete to plow. It was a ***** to push even with 800# of ballast behind the axle. I was going as easy as I could on it but it was definitely a work out.

Anyone know what might have caused this? If it's just a "thing" that happens, I'm totally cool with that. However, if this is an indicator of an issue I'd like to look into it more. The last time it did this was last year. I took it apart and found a leaky axle seal. I replaced the seals, drums, cylinders, shoes, and hardware then. Really hoping there's something else that I'm missing so I don't have to take it apart again. I hate working on the FF.

That snow was pretty wet. Could it just have been getting water inside without working the brakes hard enough to dry them out? I noticed you said it would stop when you went to a different lot, which I'd think would mean you were driving down the road at a normal-ish speed, where as in a lot, you'd be going slow.

Maybe you chewed through a new seal? Did the surfaces look ok when you were in there last?

My brakes stop hard when they're wet.

That's a good point you make. I ran through enough piles of wet snow for sure. This truck sure does do everything I ask of it without complaining or acting up. I'm hoping this was the cause. It just seems like it'd be really tough to get water up in there but I guess if I'm running over 1' drifts constantly...

The surfaces looked great when i was in there, nothing was gouged or uneven.

As for the leaky seal Timken makes a seal w/a wear sleeve in it. I had trouble with the d/s leaking and found those on Rock Auto believe it or not. People nowadays have never heard of speedy sleeves and if you find them they are stupid priced now not like years ago when they were $10 bucks. The Timken style sleeve is what the big trucks run and I have always wondered why they didn’t make them for pickups

I have the sameish truck. The rear drums lock up so easy on my gravel driveway. I imagine its not as noticeable when you are driving on a surface that gives you more friction, like pavement.

I imagine the cold snow packing around the tires, everything else, and the intermittent braking will show various performance differences.

If you test the brakes, i would say try doing it on a dry day and then test it on pavement and then gravel or dirt.

In my experience, the less road friction you have the greater your drum brakes will just lock up.

My truck does the same thing when plowing snow. Drive why lightly applying brakes on the street a few blocks and it goes away. I always assume wet brakes.

I'm pretty sure you have to above 8 mph for anti lock , anti skid to become active.