Motor vehicle air spring system having a tire-fill connection

An arrangement for filling the tire of a spare wheel in a motor vehicle equipped with an air spring system having an air supply unit, the arrangement comprising:

• a tire-fill connection unit having an air supply connection connectable to said air supply unit;
• a fill unit having an input connected to said tire-fill connection unit and an output connectable to the tire to be filled;
• said tire-fill connection unit including a proximity switch and a reed switch operatively connected to said proximity switch;
• a control apparatus;
• said reed switch having first, second and third inputs (32a, 32b, 32c) connected to said control apparatus;
• and,
• (a) said reed switch functioning in a fault-free condition to change the logic states of the first and second inputs (32a, 32b) thereof from low/high to high/low when said tire-fill connection unit is attached;
• (b) said reed switch functioning in a fault-free condition, to change the logic states of the first and second inputs (32a, 32b) from high/low to low/high when disconnecting said tire-fill connection unit;
• (c) said control apparatus functioning to detect high/high and when said high/high is detected, then either the third input (32c) has undergone a short circuit to positive or the second input (32b) has undergone a line interruption or short circuit to positive which cannot be diagnosed when said tire-fill connection unit is not attached;
• and,
• (d) said control apparatus functioning to detect low/low, then either the second input (32b) or the third input (32c) has a short circuit to ground which can be diagnosed when said tire-fill connection unit is not mechanically attached and the fill operation can be started when only one of two first and second inputs (32a, 32b) changes its logic state.