During this the upper limit of the dipped beam should remain within the limit of lines « B » and«C», If it does not, check : - that the front and rear main headlamp controls are in working order. - that the control is not too stiff, which makes the limit of the beam move jerkily. In this case ensure that : - the R.H. ventilation pipe (19) is not touching the rod of the delay device (20), They must be at least 2 mm apart.