Some owners of 2016 Buick Lacrosse or Regal vehicles may comment on a hard brake pedal on a cold startup and/or a service brake assist message.
The technician may find DTC C027B or P050F set in the BCM. On some vehicles, the connector at the KR14 brake booster pump motor relay was not fully seated.
Note that the brake booster pump relay is incorporated into the brake booster pump motor. If the connector is not fully seated, press the connector fully into the cavity.
After seating the connector, deplete brake booster vacuum by pressing the brake pedal several times with the engine off and then restart the engine and confirm that the brake booster pump runs and there is normal brake pedal function.
About the Author
Information courtesy of Mitchell 1
Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.
Mike Mavrigian
Motor Age Editor
Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.