A 2005 TOYOTA crown 3 car with a mileage of about 130 thousand km. User response: when the vehicle is above 100km/h, the ABS fault lamp, VSC/TRC/EPS fault lamp and tire pressure lamp alarm. After receiving the car: connect the TOYOTA special diagnostic device to retrieve the fault code. The ABS fault code shows: 1. The fault of the left front wheel speed sensor; second, the right front wheel speed sensor fault. The fault codes of VSC vehicle stability system and TRC anti slip traction system are: ABS control system fault code display, no speed signal input. Clear fault code, ABS left forward wheel speed sensor and right forward wheel speed sensor fault code can not be cleared, after clearing the ABS control system fault code, the ABS two front wheel speed sensor fault code can be cleared, and then clear the EPS electric steering system fault code. It is found that all fault codes are related to wheel speed sensors. After the diagnosis of ABS data flow out, the road test, at low speed, two front wheel speed sensor data normal, ABS work normal, speed signal input normal; speed to 110km/h suddenly ABS fault lamp, VSC/TRC/EPS fault lamp, tire pressure lamp alarm. Since the speed signal is taken from the wheel speed sensor through the ABS control unit, the above faults are related to the wheel speed sensor. Drive the car back to the factory for inspection, lift up the vehicle's two front wheel speed sensor wiring harness plug, firmly and without damage, and turn the data flow display on the wheel diagnostic instrument. The 10km/h signal is sensitive, and the input signal of the wheel and wheel speed sensor is not abnormal, but the chassis has obvious collision traces. The wheel speed sensor of the car is a built-in one (the bearings and sensors are sealed together), so the accessories number on the bearing of the left and right wheel is checked, and the number is found the same. Search for the crown maintenance manual. The sensor is a new type of magnetoresistance. When the wheel is rotated backward, the output voltage of the sensor is 3. 6V. When the vehicle moves forward, the sensor output voltage 2.5V, and the ABS control unit detects the forward and backward rotation of the vehicle according to the voltage of the sensor. Because of human reasons, the right front bearing is replaced by the left front bearing to make the ABS receive the wrong signal. The vehicle does not alarm at low speed. The speed input of the left and right wheel can not synchronize when the vehicle is at high speed. The control unit is misdiagnosed as the system fault, and the speed signal can not be output, causing the related system alarm. Troubleshooting after replacement. Summary of maintenance: when servicing, the extended function of ABS of the vehicle should be considered - auxiliary function of uphill braking. When the vehicle gear position is in the D position, such as the vehicle slips in the upslope (the vehicle is equivalent to reversing, the bearing is rotated backward), the wheel speed signal is input to the voltage signal of the ABS 3.6V, and the system implements the brake to prevent the vehicle from slipping, so the bearing has the right and left points.