According to GM, the culprit is a poor electrical connection in the steering gear assembly. The issue causes power steering to fail and is most notable after owners first turn the car on, though it may happen while driving, too. Unprompted loss of power steering increases the risk of a crash, though it's possible to maintain control without it. Owners may see an indicator light and hear a chime letting them know of the problem.
To fix the issue, a technician will install a new steering gear torque sensor cover assembly, which GM used in production after it built this specific batch of trucks. Other pickups also received a similar component in a separate recall campaign. All work will be done free of charge, and GM will reimburse owners who've already had repairs done, if their truck is out of warranty. Look for mailed notices starting in early May.