slip control is active u2019 or u2018 traction slip control is not active u2019 and determining the slope in dependence on the comparison result and the driving situation application_number US 50410104 A description the slope offset degree slope is composed of two components the estimated slope c slope and a safety constant c safe when the acceleration sensor or g sensor is defective it is not possible to assess a slope the determination of c slope is illustrated after a short description of the used base signals thereafter will follow information for calculating the safety constant in the non recursive approach chosen herein the difference between the acceleration of the wheels of the secondary axle e g the rear wheels tc4wdhaacc and the g sensor acceleration losenacc according to the relation is taken as an assessed value for the slope with slope representing the estimated slope of a vehicle driving forward tc4wdhaacc must mirror the true vehicle acceleration in order that slope can be used as an assessed value for the slope this applies only with stably running wheels of the secondary axle when the wheels do not run stably i e when the wheels are exposed to slip the true slope.