Brakes slightly pulling to one side.

I've jacked up the front end and both wheels spin freely. Had my son stand on the brake pedal and both lock up fine. However, the truck pulls slightly to the left when I apply the brakes. Is it possible the caliper is partial engaging/seized?

I plan on pulling the pads tonight to take a look and also checking the pins to make sure they aren't sticking.

 

I'd say it's seizing up. I had a slight pull on my first gen and didn't think anything of it. Pulled apart and changed the pads and it seized even worse after.

 

It may not be the brakes at all.

It could be an alignment issue.

 

^^^^This, and a common one.