Malfunction: a Ford Carnival car has been running for 57 thousand km. The ABS fault light on the dashboard often appears. Inspection and analysis: first read the fault code with WDS, showing the 00295 one right rear wheel speed sensor (G45) failure. The possibility of analyzing this fault code is that the speed signal is not transmitted to the ABS control unit when the speed is more than 10km/h; when the speed is greater than 40 km/h, the speed signal exceeds the standard value; the wheel speed sensor has an identifiable circuit breaker or the fault of the positive pole and the bypass. Therefore, it is considered that the following aspects should be examined: the connection between the wheel speed sensor and the ABS control unit, the clearance of the wheel speed sensor and the gear ring, the position of the installation and the pollution of the dust or impurities, and the wheel speed sensor itself. Connect the fault detector, let the engine run at idle speed, choose to read the ABS data stream and lift the vehicle with the lift. It is found that each wheel is at rest, each display area displays o km/h, the right rear wheel is turned with hand, the second display area shows 8 km/h to turn the other wheels and observe the corresponding display area, and find the display value. Basically the same. So the vehicle was lowered from the lifting machine and the fault code was cleared with WDS. The ABS fault lamp on the dashboard was extinguished, so the road test was carried out on the dashboard and everything was normal. Read the data stream with WDS and enter the second display area of the display group to see the right rear wheel speed data. It is found that when the ABS fault lamp is not lit, the data is basically the same as the other 3 wheel speeds when it is accelerated, decelerated and braking, and the function of the ABS can also feel the normal function of the ABS, and the failure does not appear. Just when preparing to return to the factory, the ABS fault light is switched on again, and the fault storage is still accidental failure of the right rear wheel speed sensor. According to the detection results of the vehicle, there is only one possibility, that is, the right back wheel speed sensor and the ABS control unit may produce instantaneous short circuit or circuit breakage. According to the circuit diagram, it is found that the terminal 8 of the 24 pin connector of the ABS control unit has a slight corrosion phenomenon, which is a signal terminal for the right rear wheel speed sensor. Troubleshooting: clean the connector terminal of the corroded ABS control unit.