21. Two tests are carried out to check the efficiency of the parking brake system of the vehicle. Those tests are carried out according to the following method:
(1) they take place on a 30% slope;
(2) the device to immobilize the powertrain, if any, is disengaged;
(3) the force applied on the parking brake control does not exceed 400 N for a hand control and 500 N for a foot control.
The first test consists in keeping the vehicle still in the slope, in one direction, for 5 minutes or more. The second test is to the same effect, but in the opposite direction.