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abs light on and speedometer not working
The ABS light is usually due to the failure of the wheel speed sensor. The ABS system does not dare to control the brake rashly when it cannot determine the speed of each wheel. Of course, the ABS control system will also light up when it has a fault. The failure of the wheel speed sensor can be basically eliminated if the speedometer does not move. At the same time, it can be determined that the ABS control system is faulty. In the early days, some vehicles without ABS did not have wheel speed sensors. The speedometer displayed the vehicle speed by reading the sensor signal on the output shaft of the transmission. Now it is basically the ABS control unit that reads the wheel speed sensor to obtain the vehicle speed signal and share it on the CAN bus. The speedometer can be read directly. If the ABS control system is OK, the speedometer will not display unless the wheel speed sensors of four wheels are broken, And this possibility is too low. Therefore, it is more likely that the ABS control unit cannot provide the vehicle speed signal.
The engine fault light confirms the "crime" of the ABS control unit. You may be surprised that ABS turns off the engine and lights up the engine. In fact, ABS is really related to the engine in some cars. There is a misfire detection program during engine operation, which constantly monitors the combustion condition in the engine cylinder. When driving on bumpy roads, the engine resistance changes violently. At this time, it is easy to be misjudged by the software. Therefore, some control systems will use the wheel speed sensor signal provided by ABS to judge whether the vehicle is driving on bumpy roads. If so, the misfire detection program will be temporarily shielded. If the ABS system cannot provide this signal, the misfire detection program will continue to run when driving on bumpy roads, and the engine will be identified as misfire, so the light will be on. Therefore, it is not difficult to draw a conclusion by combining these fault phenomena with our analysis: the failure of the ABS control system can not provide the vehicle speed signal, which leads to all these phenomena. It is likely that a fuse is burned out. Open the fuse box, there is a comparison diagram in the cover, find the insurance of the ABS system and check it. If it is damaged, replace it to solve the problem
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