【Fault description】
    The front wheel near the abnormal sound, the speed gauge pointer occasionally abnormal vibration
    【Inspection process】
    First break the brake system to check the results, the brake disc friction plate wear, but there are residual residue from the wear limit. Disc rotor does not vibrate. Wheel bearings also did not produce shoulder (step) shaped wear, brake caliper mobile parts are normal. The car is equipped with the current very popular ABS system (anti-lock braking system). Remove the sensor, check the sensor drive mechanism, the results are not unusual. Once again the test run, the results noted that very suspicious phenomenon, which is the brake sound, brake pedal rebound and speed table pointer vibration is synchronized. Consider this is the ABS system is abnormal, so pull the speed sensor connector, stop the ABS action, and then driving test. After starting the engine, ABS brake system alarm light, said ABS system abnormal. In this state the actual driving, no sound, brake pedal does not rebound, completely normal. But the speed gauge pointer is still vibrating, as if the ABS system is abnormal. However, if the electrical system is abnormal, then the ECU after the perception should stop the action, while the alarm should also be alarm. From the above analysis to see the electrical system seems to be no exception, but the fault and the speed table has some relevance, the actual check speed table, cable, driven gear, the results of the instrument body, instrument cables are not unusual, but behind the transmission with a Gearbox, which is filled with ABS system rear wheel speed sensor. This conforms to the front two wheel speed sensors, the rear side of a wheel speed sensor specification. The sensor is mounted in a one-piece form on a driven gearbox and removed to see that the gears have almost fallen off the shaft of the press fit and have been worn out by 2/3.
    【Fault Analysis】
    In this case, the ECU can not normally get the information of the drive shaft, that is, the ECU gets the drive shaft rotation signal for a while, and then the drive shaft stops the signal, and the strange signal is input continuously. ECU that the rear wheel in a locked state, so issued a command to instruct the rear wheel of the brake to reduce oil pressure. In other words, because the driven gear is abnormal, so the speed gauge pointer vibration, and the brake pedal rebound. At the same time produce the front brake noise, it should be the engine room stimulator sound.
    【Maintenance】
    Replace the rear wheel speed sensor.