Brakes pulling to the left, pulsating

It has to do with abs. You may or may not have a problem I don’t know. Normally for that to happen one or more wheels has detected a potential wheel lock up and automatically pumps the brakes ( lets up pressure) to the affected wheel.Ideally the valve that controls pressure to the axle should adjust to put less pressure to avoid a potential lock up. Normal function of valve is supposed to adjust pressure to each Front wheel to keep it from pulling either way when braking under any circumstances.Add Traction control and an excessive wheel spin will cut power to spinning wheel an apply braking to spinning wheel.If You hit brakes and it suddenly pulled one way while maybe the other wheel was sliding a little it started reacting and simply did it’s job as designed. But if it started pulling after all the pulsating I think their may be a problem.It can be diagnosed by checking stored codes if it’s an intermittent problem. Otherwise if there’s an active problem usually the abs or traction control light will come on to let you know. It’s common on any newer car driving in snow and slam on brakes pedal goes nuts pulsating.First time it happened to me on a new car I thought I had a problem Lol Perfectly normal.But if you have a constant pull while braking there’s definitely a problem somewhere could be any thing from oil soaked shoes/ pads to bad sensor/ or relay valve etc. If so get it fixed asap

 

I should say I’m not a mechanic just trying to help.I just fixed a few issues this week on my abs and read up quite a bit. A qualified mechanic would have more info

 

Had that happen once a few years ago after the first heavy rain of the year. There was a build up of dirt and rust on the inner part of my brake drums. There is a strip on the inner drum that the shoes don't touch and can collect crud. I drive mostly in CA and NV so don't see rain much. Pulled drums and the shoes were covered in dust and crud. Replaced shoes and drums good to go. Not saying that is what is happening to you but you might look at your shoes to see.

 

Take that truck to the shop of relatively clean and good quality.

In my time when I was trained on brake and alingment rack, the first thing we did was blow out dirt, dust, shoe dust (Brake pads, probably abestos from those days. Cought cought... with the airgun. PFFFTH.

Now let's eyeball the disc, drum, pads for wear problems and work deeper. Lastly but not least is a fluid that is added, then bled until all the air is out. In this case, its air pressure. (OR in UK Vacumn in terms of train)

In terms of heavy truck or any vehicle you really need to examine that whole system. And remember that Pads are cheap. Rotors and drums are not.

 

I had a broken wire, going to the drivers steer. Was doing the same as your talking about. Fixed the broken wire, now works perfect.