The brakes on my 1990 buick lesabre were working just fine, now all of a sudden they dont work when u put it in reverse at all, but when u go forward when u push the pedal halfway down it grabs and then it just lets go and the car keeps going
Check for leak at brake hose on front wheels and rear hose. Check rear wheel cylinders for leaking. Check master cylinder leaking at the rear where rod pushes the piston in. Remove from booster to get a visual. Check fluid.