The contact owns a 2018 Chevrolet Equinox. The contact stated that while driving at an undisclosed speed, the service brake assists warning light illuminated. The contact stated that right after the warning light illuminated, the contact rear-ended the vehicle in front. The vehicle was taken to an independent mechanic, but the failure could not be duplicated. The contact stated that the failure had reoccurred. The contact stated that the brakes were inoperable. The contact stated that the brakes were inoperable for approximately 10 seconds while driving 40 MPH on a busy roadway. The vehicle was taken to the dealer where it was diagnosed with a failed vacuum pump for the braking system. The contact was informed that the vacuum pump needed to be replaced. The vehicle was being repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 65,500.