At a glance
What can fail
Brake fluid without corrosion protection may cause the anti-lock brake module to corrode, leading to longer brake pedal travel, reduced braking power, vehicle instability, or rear wheel lockup.
What the fix does
Dealer will inspect and replace the ABS module if needed, change the brake fluid, and provide instructions to use only GM-recommended brake fluid.
Summarized — see the official notice for exact wording, dates, and contacts.