Slip control system for motor vehicle

A slip control system for a motor vehicle controlling slips in driving wheels comprising:

• means for detecting a slip ratio of each driving wheel;
• traction control means for decreasing a slip of each driving wheel by controlling a driving force transmitted to each driving wheel so that the slip ratio of each driving wheel is at least equal to a predetermined desired slip ratio when the slip ratio of the driving wheel becomes equal to the desired slip ratio;
• means for controlling an automatic transmission by using a first shift property for a normal operation and a second shift property for a traction control operation which is adapted to determine a relative higher speed stage;
• means for switching the first shift property to the second shift property when the traction control operation is started by the traction control means;
• and
• means for prohibiting the automatic transmission from shifting up in a predetermined time after said traction control means starts to control the driving force.