An automatic traction control system is provided for an electric or hybrid-electric vehicle. The automatic traction control system may be used with vehicles using two separately excited motors where the armatures of the motors are connected in series to provide differential control. The automatic traction control system monitors and compares the voltages across the armatures of the two motors. If the voltage differential exceeds a predetermined threshold, it is determined that one of the wheels is spinning and current is diverted from the motor driving the spinning wheel to the motor driving the non-spinning wheel.