Pulsing or grabbing of brakes on GMC Sierra pickup

Get some new pads and have the rotors turned. (or just get some new rotors)

Pulsating brakes are likely caused by lateral runout (LRO). Remove any rust from the hubs and have the discs turned only on a ProCut Machine, in order to eliminate the LRO. Most Firestone stores use this OEM-approved method of turning discs. Afterwards, clean and lubricate the caliper pins with silicone grease, install OEM pads, and change the brake fluid. Ensure the new pads are the same composition that originally came on the truck.

This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1618425