ECM receive vehicle speed signal from ABS/ESP (HECU, Hydraulic Electrical Control Unit) module. HECU calculates vehicle speed after receiving 4 wheel speed signal from each wheel. Then, it sends vehicle speed signal to ECM, cluster, air conditioner control module, and BCM etc. through CAN communication. If more than one of wheel speed sensor on the rear if failed, it is calculated as vehicle speed signals from 2 wheel speed sensor on the front.