The present invention relates to an automatic inter-axle differential sensor configuration (i.e., location) and calibration method for a vehicle having a tandem drive axle. The method involves determining the speed of the vehicle, determining pulses per minute from each inter-axle differential sensor via the vehicle electronic control unit (ECU), where each of the inter-axle differential sensors are connected to an inter-axle differential gear, determining a location of each inter-axle differential sensor from each of the inter-axle differential sensor pulses per minute, and assigning a number of teeth to each of the inter-axle differential gears in calibrating each of the inter-axle differential sensors. The revolutions per minute for each of the inter-axle differential sensors may be utilized to lock the inter-axle differential during slippage of the vehicle, without human intervention.