Check the vacuum line to the power brake booster. it should have vacuum when the engine is running. if it does, the booster has failed and needs to be replaced. if it does not have a vacuum, check the hose as it may be broken or loose.
Roy
Feb 11, 2018 at 5:19 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.