變速箱的控制單元從安裝在變速箱上和車輛上的諸多傳感器如：車速傳感器、變速箱輸入轉速傳感器、變速箱輸出轉速傳感器、發(fā)動機轉速傳感器、油門踏板位置傳感器等等采集信號，經過數據處理后發(fā)送指令給執(zhí)行機構如：電磁閥N88-N94,從而控制相應的換擋離合器或制動帶工作使變速箱換入相應的檔位。

The control unit of the gearbox collects signals from various sensors installed on the gearbox and vehicle, such as the vehicle speed sensor, gearbox input speed sensor, gearbox output speed sensor, engine speed sensor, accelerator pedal position sensor, etc. After data processing, it sends instructions to the executing mechanism, such as solenoid valve N88-N94, to control the corresponding shift clutch or brake band to work and shift the gearbox into the corresponding gear.

本案例的故障出現(xiàn)在電控系統(tǒng)部分，產生故障碼“17105 P0721 035-輸出轉速傳感器電路范圍/性能間隙式”的原因分析如下：

The fault in this case occurred in the electronic control system, and the cause of the fault code "17105 P0721 035 Output Speed Sensor Circuit Range/Performance Gap Type" is analyzed as follows:

(1)按照正常的信號處理順序：車速信號首先進入到儀表，經過儀表控制單元進行處理后通過CAN數據總線送給各個ECU。變速箱的ECU從CAN數據總線上取得車速信號進行換擋控制。

(1) According to the normal signal processing sequence: the vehicle speed signal first enters the instrument panel, and after being processed by the instrument control unit, it is sent to various ECUs through the CAN data bus. The ECU of the gearbox obtains the vehicle speed signal from the CAN data bus for gear shift control.

(2) G38是輸出轉速傳感器，它和輸入轉速傳感器G 192配合計算現(xiàn)在的檔位，為下次換擋做準備。發(fā)動機轉速和車速是變速箱進行換擋控制的兩個主要數據，當變速箱的ECU無法識別車速時，換擋也就無從操控，變速箱將進入到緊急運行功能中。

(2) G38 is an output speed sensor that works in conjunction with input speed sensor G 192 to calculate the current gear position and prepare for the next gear shift. The engine speed and vehicle speed are the two main data for shifting control of the gearbox. When the ECU of the gearbox cannot recognize the vehicle speed, shifting cannot be controlled, and the gearbox will enter the emergency operation function.

(3)變速箱根據發(fā)動機轉速信號、變速箱輸入轉速G 182的信號和輸出轉速G38的信號，結合車速傳感器G22的信號決定換擋。但是此時車速信號變換不定：從0-255-154-80公里/小時等亂變，因此在換擋程序設定的范圍內ECU無法判斷清楚，故給出了上述故障碼。

(3) The gearbox determines gear shifting based on the engine speed signal, the input speed signal G 182, and the output speed signal G38, combined with the signal from the vehicle speed sensor G22. However, at this time, the speed signal changes unpredictably, ranging from 0-255-154-80 kilometers per hour, etc. Therefore, the ECU cannot determine clearly within the range set by the gear shift program, and the above fault code is given.

(4)由于大燈控制單元浸泡在水中，導致CAN數據總線工作失常，進而影響到車速信號的正確發(fā)送，當車速信號發(fā)送正確時，變速箱工作正常；當車速信號發(fā)送不正確時，變速箱工作不正常。因而會有變速箱問歇性的故障。經過觀察分析，我們發(fā)現(xiàn)車輛的后風擋玻璃在貼太陽膜時噴的水非常后都流進了大燈控制單元里，導致了變速箱的工作不正常。

(4) Due to the headlight control unit being immersed in water, the CAN data bus malfunctioned, which in turn affected the correct transmission of the vehicle speed signal. When the vehicle speed signal is transmitted correctly, the gearbox works normally; When the vehicle speed signal is sent incorrectly, the gearbox is not working properly. Therefore, there may be intermittent faults in the gearbox. After observation and analysis, we found that the water sprayed on the rear windshield of the vehicle when applying the solar film eventually flowed into the headlight control unit, causing abnormal operation of the gearbox.